Final Environmental Assessment Rangeland Grasshopper 

and Mormon Cricket Suppression Program

Wyoming

EA Number: WY-20-01

Prepared by:

Animal and Plant Health Inspection Service

Plant Protection and Quarantine

5353 Yellowstone Road

Suite 208

Cheyenne, Wyoming 82009

Office Phone: 307-432-7979

Office Fax: 307-432-7970

June

2020
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Table of Contents

I. Need for Proposed Action...................................................................................................... 6

A. Purpose and Need Statement .............................................................................................. 6

B. Background Discussion ...................................................................................................... 6

C. About This Process............................................................................................................. 9

II. Alternatives............................................................................................................................ 9

A. No Suppression Program Alternative ............................................................................... 10

B. Insecticide Applications at Conventional Rates or Reduced Agent Area Treatments with 

Adaptive Management Strategy (Preferred Alternative)........................................................ 10

C. Research Treatments Alternative...................................................................................... 12

1. Methods Development Studies...................................................................................... 12

2. Pesticides and Biopesticides Used in Studies................................................................ 13

III. Affected Environment.......................................................................................................... 15

A. Description of Affected Environment............................................................................... 15

B. Other Considerations ........................................................................................................ 16

1. Human Health ................................................................................................................ 16

2. Non-target Species......................................................................................................... 17

3. Socioeconomic Issues.................................................................................................... 23

4. Cultural Resources and Events ...................................................................................... 24

5. Special Considerations for Certain Populations ............................................................ 24

IV. Environmental Consequences.............................................................................................. 26

A. Environmental Consequences of the Alternatives............................................................ 26

1. No Suppression Program Alternative ............................................................................ 26

2. Insecticide Applications at Conventional Rates or Reduced Agent Area Treatments 

with Adaptive Management Strategy.................................................................................... 27

3. Research Treatments Alternative................................................................................... 37

B. Other Environmental Considerations................................................................................ 39

1. Cumulative Impacts....................................................................................................... 39

2. Endangered Species Act ................................................................................................ 40

3. Monitoring ..................................................................................................................... 41

4. Fires and Human Health Hazards.................................................................................. 42

V. Literature Cited .................................................................................................................... 43

VI. Listing of Agencies and Persons Consulted......................................................................... 51

Appendix 1: APHIS Rangeland Grasshopper and Mormon Cricket Suppression Program FY2020 Treatment Guidelines............................................................................................................. 2

Appendix 2: USFWS/NMFS/WGFD Correspondence ................................................................. 6

Appendix 3: Summary of Species Determinations and Impact Mitigation Measures.................. 12

Appendix 4: Yellow-billed cuckoo (YBC) risk summary for grasshopper and Mormon cricket 

suppression program..................................................................................................................... 26

Appendix 5: Northern long-eared bat (NLEB) risk summary for grasshopper and Mormon cricket 

suppression program..................................................................................................................... 30

Appendix 6: Comments received during the open comment period............................................. 34

Appendix 7: 2019 Adult Grasshopper Survey Map.................................................................... 100

Appendix 8: Completed FONSI.................................................................................................. 101
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Acronyms and Abbreviations

ac acre

a.i. active ingredient

AChE acetylcholinesterase

APHIS Animal and Plant Health Inspection Service 

ATV All Terrain Vehicle

BIA Bureau of Indian Affairs

BCF bioconcentration factor 

BLM Bureau of Land Management

CEQ Council of Environmental Quality

CFR Code of Federal Regulations

EA environmental assessment

e.g. example given (Latin, exempli gratia, “for the sake of example”)

EIS environmental impact statement

E.O. Executive Order

oF degrees Fahrenheit

FAASSTT Field Aerial Application Spray Simulation Tower Technique

Fl. Oz. fluid ounce

FONSI finding of no significant impact

FR Federal Register

FS Forest Service

IMP Interim Management Policy

HHERA human health and ecological risk assessments

i.e. in explanation (Latin, id est “in other words.”)

IPM integrated pest management

lb pound

LWG Local Working Group

MBTA Migratory Bird Treaty Act

ml milliliters

MOU memorandum of understanding 

MRAATs Modified reduced agent area treatments

NEPA National Environmental Policy Act 

NHPA National Historic Preservation Act 

NIH National Institute of Health

ppm parts per million

PPE personal protective equipment 

PPQ Plant Protection and Quarantine 

RAATs reduced agent area treatments 

SGCN Species of Greatest Conservation Need

S&T Science and Technology

UAS Unmanned Aircraft Systems

ULV ultra-low volume

U.S.C. United States Code

USDA United States Department of Agriculture 

USEPA United States Environmental Protection Agency

USFS United States Forest Service
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USFWS United States Fish and Wildlife Services

WGFD Wyoming Game and Fish Department

WSA Wilderness Study Area
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Final Environmental Assessment 

Rangeland Grasshopper and Mormon Cricket Suppression Program

Wyoming

I. Need for Proposed Action

A. Purpose and Need Statement

An infestation of grasshoppers or Mormon crickets may occur in Wyoming. The Animal 

and Plant Health Inspection Service (APHIS) and any cooperating agency, based on 

location of infestation may, upon request by land managers or state departments of 

agriculture, conduct treatments to suppress grasshopper and/or Mormon cricket

infestations as part of the Rangeland Grasshopper and Mormon Cricket Suppression 

Program (Program). The term “grasshopper” used in this environmental assessment (EA)

refers to both grasshoppers and Mormon crickets, unless differentiation is otherwise 

noted.

Populations of grasshoppers that trigger the need for a suppression program are normally 

considered on a case-by-case basis. Participation in grasshopper suppression programs is 

based on potential damage, such as reduced forage, and benefits of treatments which 

include reduction of pest outbreak populations and control of incipient pest populations.

The goal of the proposed suppression program analyzed in this EA is to reduce 

grasshopper populations to economically acceptable levels in order to protect rangeland 

ecosystems or cropland adjacent to rangeland.

This EA analyzes potential effects of the proposed action and its alternatives. This EA 

applies to a proposed suppression program that would take place from March 1 to August 

31, 2020 in Wyoming. 

This EA is prepared in accordance with the requirements under the National 

Environmental Policy Act of 1969 (NEPA) (42 United States Code § 4321 et. seq.) and 

the NEPA procedural requirements promulgated by the Council on Environmental 

Quality, United States Department of Agriculture (USDA), and APHIS. A decision will 

be made by APHIS based on the analysis presented in this EA, the results of public 

involvement, and consultation with other agencies and individuals. A selection of one of 

the program alternatives will be made by APHIS for the 2020 Control Program for

Wyoming.

B. Background Discussion

Rangelands provide many goods and services, including food, fiber, recreational 

opportunities, and grazing land for cattle (Havstad et al., 2007; Follett and Reed, 2010). 

Grasshoppers and Mormon crickets are part of rangeland ecosystems, serving as food for 

wildlife and playing an important role in nutrient cycling. However, grasshoppers and 

Mormon crickets have the potential to occur at high population levels (Belovsky et al., 
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1996) that result in competition with livestock and other herbivores for rangeland forage 

and can result in damage to rangeland plant species.

In rangeland ecosystem areas of the United States, grasshopper populations can build up 

to economic infestation levels1 despite even the best land management and other efforts 

to prevent outbreaks. At such a time, a rapid and effective response may be requested and 

needed to reduce the destruction of rangeland vegetation. In some cases, a response is 

needed to prevent grasshopper migration to cropland adjacent to rangeland. 

APHIS surveys grasshopper populations on rangeland in the western United States, 

provides technical assistance on grasshopper management to landowners and land 

managers, and may cooperatively suppress grasshoppers when direct intervention is 

requested by a Federal land management agency or a State agriculture department (on 

behalf of a State or local government, or a private group or individual). The need for a 

rapid and effective response when an outbreak occurs limits the options available to 

APHIS. The application of an insecticide within all or part of the outbreak area is the 

response available to APHIS to rapidly suppress or reduce, but not eradicate, grasshopper 

populations and effectively protect rangeland. 

In June 2002, APHIS completed an environmental impact statement (EIS) document 

concerning suppression of grasshopper populations in 17 western states (Rangeland 

Grasshopper and Mormon Cricket Suppression Program, Environmental Impact 

Statement, June 21, 2002). The EIS described the actions available to APHIS to reduce 

the damage caused by grasshopper populations in Arizona, California, Colorado, Idaho, 

Kansas, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, 

South Dakota, Texas, Utah, Washington, and Wyoming. During November 2019, APHIS 

published an updated EIS to incorporate the available data and analyze the environmental 

risk of new program tools. The risk analysis in the 2019 EIS is incorporated by reference. 

APHIS will follow all state laws regarding pesticide application including Wyoming 

State Statutes §35-7-350 through §35-7-375 

(http://legisweb.state.wy.us/lsoweb/wystatutes.aspx) and Chapter 28 Rules and 

Regulations, State of Wyoming, (http://soswy.state.wy.us/Rules/default.aspx).

In November 2019, APHIS and the United States Forest Service (USFS) signed a 

Memorandum of Understanding (MOU) detailing cooperative efforts between the two 

groups on suppression of grasshoppers and Mormon crickets on National Forest system 

lands (Document #19-8100-0573-MU, November 6, 2019). This MOU clarifies that 

 1 The “economic infestation level” is a measurement of the economic losses caused by a particular population level 

of grasshoppers to the infested rangeland. This value is determined on a case-by-case basis with knowledge of many 

factors including, but not limited to, the following: economic use of available forage or crops; grasshopper species, 

age, and density present; rangeland productivity and composition; accessibility and cost of alternative forage; and 

weather patterns. In decision making, the level of economic infestation is balanced against the cost of treating to 

determine an “economic threshold” below which there would not be an overall benefit for the treatment. Short-term 

economic benefits accrue during the years of treatments, but additional long-term benefit may accrue and be 

considered in deciding the total value gained by treatment. Additional losses to rangeland habitat and cultural and 

personal values (e.g., aesthetics and cultural resources), although a part of decision making, are not part of the 

economic values in determining the necessity of treatment.
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APHIS will prepare and issue to the public environmental documents that evaluate 

potential impacts associated with proposed measures to suppress economically damaging 

grasshopper and Mormon cricket populations. The MOU also states that these 

documents will be prepared under the APHIS NEPA implementing procedures with 

cooperation and input from the USFS.

The MOU further states that the responsible USFS official will request in writing the 

inclusion of appropriate lands in the APHIS suppression project when treatment on 

national forest land is necessary. According to the provisions of the MOU, APHIS can 

begin treatments after APHIS issues an appropriate decision document.

In October 2015, APHIS and the Bureau of Land Management (BLM) signed a

Memorandum of Understanding (MOU) detailing cooperative efforts between the two 

groups on suppression of grasshoppers and Mormon crickets on BLM lands (Document 

#15-8100-0870-MU, October 15, 2015). This MOU clarifies that APHIS will prepare 

and issue to the public environmental documents that evaluate potential impacts 

associated with proposed measures to suppress economically damaging grasshopper and 

Mormon cricket populations. The MOU also states that these documents will be prepared 

under the APHIS NEPA implementing procedures with cooperation and input from the 

BLM.

The MOU further states that the responsible BLM official will request in writing the 

inclusion of appropriate lands in the APHIS suppression project when treatment on BLM 

land is necessary. The BLM must also prepare a Pesticide Use Proposal (Form FS-2100-

2) for APHIS to treat infestations. According to the provisions of the MOU, APHIS can 

begin treatments after APHIS issues an appropriate decision document and BLM 

prepares and approves the Pesticide Use Proposal.

In September 2016, APHIS and the Bureau of Indian Affairs (BIA) signed a 

Memorandum of Understanding (MOU) detailing cooperative efforts between the two 

groups on suppression of grasshoppers and Mormon crickets on BIA lands (Document 

#10-8100-0941-MU, September 16, 2016). This MOU clarifies that APHIS will prepare 

and issue to the public environmental documents that evaluate potential impacts 

associated with proposed measures to suppress economically damaging grasshopper and 

Mormon cricket populations. The MOU also states that these documents will be prepared 

under the APHIS NEPA implementing procedures with cooperation and input from the 

BIA.

The MOU further states that the responsible BIA official will request in writing the 

inclusion of appropriate lands in the APHIS suppression project when treatment on BIA 

land is necessary. The request should include the dates and locations of all tribal 

ceremonies and cultural events, as well as “not to be treated” areas that will be in or near 

the proposed treatment block(s). According to the provisions of the MOU, APHIS can 

begin treatments after APHIS issues an appropriate decision document.
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C. About This Process

The EA process for grasshopper management is complicated by the fact that there is very 

little time between requests for treatment and the need for APHIS to take action with 

respect to those requests. Surveys help to determine general areas, among the scores of 

millions of acres that potentially could be affected, where grasshopper infestations may 

occur in the spring of the following year. There is considerable uncertainty, however, in 

the forecasts, so that framing specific proposals for analysis under NEPA is not possible. 

At the same time, the program strives to alert the public in a timely manner to its more 

concrete treatment plans and avoid or minimize harm to the environment in implementing 

those plans.

The current EIS provides a solid analytical and regulatory foundation; however, it may 

not be enough to satisfy NEPA completely for actual treatment proposals, and the 

“conventional” EA process will seldom, if ever, meet the program’s timeframe of need. 

Thus, a two-stage NEPA process has been designed to accommodate such situations. For 

the first stage, this EA will analyze aspects of environmental quality that could be

affected by grasshopper treatment in Wyoming. This EA and Finding of No Significant 

Impact (FONSI) will be made available to the public for a 30-day comment period. If 

comments are received during the comment period, they will be addressed in stage two of 

the process. For stage two, when the program receives a treatment request and 

determines that treatment is necessary, the specific site within Wyoming will be 

extensively examined to determine if environmental issues exist that were not covered in 

this EA and FONSI. This stage is intended mainly to ensure that significant impacts in 

the specific treatment area will not be experienced. A supplemental determination will be 

prepared to document this finding and would also address any comments received on this 

EA. Supplemental determinations prepared for specific treatment sites will be provided 

to all parties who comment on this EA.

II. Alternatives

To engage in comprehensive NEPA risk analysis APHIS must frame potential agency 

decisions into distinct alternative actions. These program alternatives are then evaluated 

to determine the significance of environmental effects. The 2002 EIS presented three 

alternatives: (A) No Suppression; (B) Insecticide Applications at Conventional Rates and 

Complete Area Coverage; and (C) Reduced Agent Area Treatments (RAATs), and their 

potential impacts were described and analyzed in detail. The 2019 EIS was tiered to, and 

updated the 2002 EIS. The 2019 EIS provides updates to the program with new 

information and technologies that were not analyzed in the 2002 EIS. Copies of the 

complete 2002 and 2019 EIS documents are available for review at USDA APHIS PPQ, 

5353 Yellowstone Road, Suite 208, Cheyenne, Wyoming. These documents are also 

available at the Rangeland Grasshopper and Mormon Cricket Program website, 

http://www.aphis.usda.gov/plant-health/grasshopper. 

The 2019 EIS is intended to explore and explain potential environmental effects 

associated with grasshopper suppression programs that could occur in 17 western states 

(Arizona, California, Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, New 

Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, and 
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Wyoming). The 2019 EIS outlines the importance of grasshoppers as a natural part of the 

rangeland ecosystem. However, grasshopper outbreaks can compete with livestock and 

wildlife for rangeland forage and cause devastating damage to crops and rangeland 

ecosystems. Rather than opting for a specific proposed action from the alternatives 

presented, the 2019 EIS analyzes in detail the environmental impacts associated with 

each programmatic action alternative related to grasshopper suppression based on new 

information and technologies.

All insecticides used by APHIS for grasshopper suppression are used in accordance with 

applicable product label instructions and restrictions. Representative product specimen 

labels can be accessed at the Crop Data Management Systems, Incorporated website at 

www.cdms.net/manuf/manuf.asp. Labels for actual products used in suppression 

programs will vary, depending on supplier. All insecticide treatments conducted by 

APHIS will be implemented in accordance with APHIS’ treatment guidelines and 

operational procedures, included as Appendix 1 to this final EA. 

This Final EA analyzes the significance of environmental effects that could result from 

the alternatives described below. These alternatives differ from those described in the 

2019 EIS because grasshopper treatments are not likely to occur in most of Wyoming and 

therefore the environmental baseline should describe a no suppression scenario.

A. No Suppression Program Alternative

Under Alternative A, the No Suppression alternative, APHIS would not fund or 

participate in a program to suppress grasshopper infestations within Wyoming. Under this 

alternative, APHIS may opt to provide limited technical assistance, but any suppression 

program would be implemented by a Federal land management agency, a State 

agriculture department, a local government, or a private group or individual.

B. Insecticide Applications at Conventional Rates or Reduced Agent 

Area Treatments with Adaptive Management Strategy (Preferred 

Alternative)

Under Alternative B, the preferred alternative, APHIS would manage a grasshopper 

treatment program using techniques and tools discussed hereafter to suppress grasshopper 

outbreaks. The insecticides available for use by APHIS include the U.S. Environmental 

Protection Agency (USEPA) registered chemicals malathion, carbaryl, and 

diflubenzuron. These chemicals have varied modes of action: carbaryl and malathion 

work by inhibiting acetylcholinesterase (AChE) (enzymes involved in nerve impulses);

and diflubenzuron is a chitin inhibitor. APHIS would make a single application per year 

to a treatment area and could apply insecticide at an APHIS rate conventionally used for 

grasshopper suppression treatments, or more typically as reduced agent and area 

treatments (RAATs). APHIS selects which insecticides and rates are appropriate for 

suppression of a grasshopper outbreak based on several biological, logistical, 

environmental, and economical criteria. The identification of grasshopper species and 

their life stage largely determines the choice of insecticides used among those available 

to the program. RAATs are the most common and preferred application method for all 
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program insecticides, and only rarely do rangeland pest conditions warrant full coverage 

and higher rates.

The RAATs strategy is effective for grasshopper suppression because the insecticide 

controls grasshoppers within treated swaths while conserving natural grasshopper 

predators in swaths not directly treated. RAATs can decrease the rate of insecticide 

applied by either using lower insecticide concentrations or decreasing the deposition of 

insecticide applied by alternating one or more treatment swaths. Both options are most 

often incorporated simultaneously into RAATs. Either malathion, carbaryl, or

diflubenzuron would be considered under this alternative (with diflubenzuron being the 

preferred chemical) typically at the following application rates:

• 4.0 fluid ounces (0.31 pounds active ingredient (lb a.i.)) of malathion per acre;

• 8.0 fluid ounces (0.25 lb a.i.) of carbaryl ULV spray per acre;

• 10.0 pounds (0.20 lb a.i.) of 2 percent carbaryl bait per acre;

• 0.75 or 1.0 fluid ounce (0.012 lb a.i.) of diflubenzuron per acre.

The width of the area not directly treated (the untreated swath) under the RAATs 

approach is not standardized but has minimum and maximum parameters. The proportion 

of land treated in a RAATs approach is a complex function of the rate of grasshopper 

movement, which is a function of developmental stage, population density, and weather 

(Narisu et al., 1999, 2000), as well as the properties of the insecticide (insecticides with 

longer residuals allow wider spacing between treated swaths). Foster et al. (2000) left 20 

to 50% of their study plots untreated, while Lockwood et al. (2000) left 20 to 67% of 

their treatment areas untreated. Currently the grasshopper program typically leaves 50% 

of a spray block untreated for ground applications where the swath width is between 20 

and 45 feet. For aerial applications, the skipped swath width is typically no more than 20 

feet for malathion, 100 feet for carbaryl and 200 feet for diflubenzuron. The selection of 

insecticide and the use of an associated swath width is site dependent. Rather than 

suppress grasshopper populations to the greatest extent possible, the goal of this 

alternative is to suppress grasshopper populations to a desired level.

Insecticide applications at conventional rates and complete area coverage, is an approach 

that APHIS has used in the past but is currently uncommon. Under this option, malathion, 

carbaryl, or diflubenzuron would cover all treatable sites within the designated treatment 

block per label directions. The application rates under this option are typically at the 

following application rates:

• 8.0 fluid ounces (0.62 lb a.i.) of malathion per acre;

• 16.0 fluid ounces (0.50 lb a.i.) of carbaryl spray per acre;

• 10.0 pounds (0.50 lb a.i.) of 5 percent carbaryl bait per acre;

• 1.0 fluid ounce (0.016 lb a.i.) of diflubenzuron per acre.

The potential generalized environmental effects of the application of malathion, carbaryl, 

and diflubenzuron, under this alternative are discussed in detail in the 2019 EIS. A 
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description of anticipated site-specific impacts from this alternative may be found in Part 

IV of this document.

C. Research Treatments Alternative

APHIS PPQ continues to refine its methods of grasshopper and Mormon cricket 

management in order to improve the abilities of the Rangeland Grasshopper and Mormon 

Cricket Suppression Program (herein referred to as the Program) to make it more 

economically feasible, and environmentally acceptable. These refinements can include 

reduced rates of currently used pesticides, improved formulations, development of more 

target-specific baits, development of biological pesticide suppression alternatives, and 

improvements to aerial (e.g., incorporating the use of Unmanned Aircraft Systems 

(UAS)) and ground application equipment. A division of APHIS PPQ, Science and 

Technology’s (S&T) Phoenix Lab, located in Arizona, and its Rangeland Grasshopper 

and Mormon Cricket Management Team (Rangeland Unit) conducts methods 

development and evaluations on behalf of the Program. The Rangeland Unit’s primary 

mission is to comply with Section 7717 of the Plant Protection Act and protect the health 

of rangelands (wildlife habitats and where domestic livestock graze) against 

economically damaging cyclical outbreaks of grasshoppers and Mormon crickets. The 

Rangeland Unit tests and develops more effective, economical, and less environmentally 

harmful management methods for the Program and its federal, state, tribal, and private 

stakeholders.

To achieve this mission, research plots ranging in area from less than one foot to 640 

acres are used and often replicated. The primary purpose of these experiments is to test 

and develop improved methods of management for grasshoppers and Mormon crickets. 

This often includes testing and refining pesticide and biopesticide formulations that may 

be incorporated into the Program. These investigations often occur in the summer (MayAugust) and the locations typically vary annually. The plots often include “no treatment” 

(or control) areas that are monitored to compare with treated areas. Some of these plots 

may be monitored for additional years to gather information on the effects of utilized 

pesticides on non-target arthropods. Note that an Experimental Use Permit is not needed 

when testing non-labeled experimental pesticides if the use is limited to laboratory or 

greenhouse tests, or limited replicated field trials involving 10 acres or less per pest for 

terrestrial tests.

Studies and research plots are typically located on large acreages of rangelands and the 

Rangeland Unit often works on private land with the permission of landowners. 

Locations of research trials will be made available to the appropriate agencies in order to 

ensure these activities are not conducted near sensitive species or habitats. Due to the 

small size of the research plots, no adverse effects to the environment, including 

protected species and their critical habitats, are expected, and great care is taken to avoid 

sensitive areas of concern prior to initiating studies.

1. Methods Development Studies

Methods development studies may use planes and all-terrain vehicles (ATVs) to apply 

labeled pesticides using conventional applications and the reduced agent area treatments 
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(RAATs) methodology. The experiments may include the use of an ultra-low volume 

sprayer system for applying biopesticides (such as native fungal pathogens). Mixtures of 

native pathogens and low doses of pesticides may be conducted to determine if these 

multiple stressor combinations enhance mortality. Aircraft will be operated by Federal 

Aviation Administration licensed pilots with an aerial pesticide applicator’s permit. 

The Rangeland Unit often uses one square foot micro plots covered by various types of 

cages depending on the study type and species used. These types of study plots are 

preferred for Mormon cricket treatments and those involving non-labeled research

pesticides or biopesticides. The most common application method for micro plots is 

simulating aerial applications via the Field Aerial Application Spray Simulation Tower 

Technique (FAASSTT). This system consists of a large tube enclosed on all sides except 

for the bottom, so micro plot treatments can be accurately applied to only the intended 

treatment target. Treatments are applied with the FAASSTT in micro doses via a syringe 

and airbrush apparatus mounted in the top.

The Rangeland Unit is also investigating the potential use of Unmanned Aerial Systems 

(UAS) for a number of purposes related to grasshopper and Mormon cricket detection 

and treatment. UAS will be operated by FAA licensed pilots with an aerial pesticide 

applicator’s permit.

2. Pesticides and Biopesticides Used in Studies

 Pesticides likely to be involved in studies currently include:

1) Liquids: diflubenzuron (Dimilin 2L and generics: currently Unforgiven and Cavalier 

2L) and chlorantraniliprole (Prevathon). Program standard application rates are: 

diflubenzuron - 1.0 fl. oz./acre in a total volume of 31 fl. oz./acre; chlorantraniliprole 

- 2.0 fl. oz./acre (RAATs) or 4.0 fl. oz./acre (conventional coverage), both in a total 

volume of 32 fl. oz./acre. Research rates often vary, but the doses are lower than 

standard Program rates unless otherwise noted. 

2) Baits: carbaryl. Program standard application rates: 2% bait at 10 lbs./acre (2 lbs. 

AI/acre) or 5% bait at 4 lbs./acre (2 lbs. AI/acre). 

3) LinOilEx (Formulation 103), a proprietary combination of easily available natural 

oils and some commonly encountered household products, created by Manfred 

Hartbauer, University of Graz, Austria. Note that LinOilEx (Formulation 103) is 

experimental; for more information, see “Potential Impacts of LinOilEx 

Applications” in the section “Information on Experimental Treatments.”

 Biopesticides likely to be involved in studies currently include: 

1) Metarhizium robertsii (isolate DWR2009), a native fungal pathogen. Note that 

Metarhizium robertsii (isolate DWR2009) is experimental; for more information, see 

“Potential Impacts of Metarhizium robertsii Applications” in the section “Information 

on Experimental Treatments.”
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2) Beauveria bassiana GHA, a native fungal pathogen sold commercially and registered 

for use across the U.S.

At this time, it is undecided where in the 17 western states research will be conducted. 

The final location decision is dependent upon grasshopper and/or Mormon cricket 

population densities and availability of suitable sites. It is most likely research will be 

conducted in Arizona, Idaho, New Mexico, Oregon, Montana, or Washington. Potential 

research studies are as follows:

Study 1: Evaluate efficacy of a UAS-mounted bait spreader applying 2% carbaryl bait at 

5 lbs/acre. This study plans to use replicated 40 acre plots (320 acres total) on Colville 

Confederated Tribes land in Washington sometime in May/June, but is contingent upon a 

population of sufficient size. Mortality will be then be observed for a duration of time to 

determine efficacy.

Study 2: Evaluate persistence of the experimental biopesticide DWR2009 in bait form by 

coating wheat bran with the pathogen. A grasshopper species of local abundance will be 

placed into replicated microplot cages and fed the baits by hand. Mortality and 

sporulation will then be observed for a duration of time to determine persistence in both 

the field and the lab.

Study 3: Evaluate efficacy of the experimental biopesticide DWR2009 in bait form by 

coating wheat bran with the pathogen. A grasshopper species of local abundance will be 

placed into replicated microplot cages and fed the baits by hand. Mortality and 

sporulation will be then be observed for a duration of time to determine efficacy in both 

the field and the lab. 

Study 4: A stressor study to evaluate efficacy of the experimental biopesticide DWR2009 

in liquid form when combined with Dimilin 2L. The FAASSTT will be utilized to apply 

varying dose levels of Dimilin 2L (below label rates) in order to compare efficacy, 

starting at the rate of 1.0 fl. oz./acre. Replicated microplots will be treated and then a 

grasshopper species of local abundance will be placed into each cage. Mortality will be 

then be observed for a duration of time to determine efficacy.

Study 5: Evaluate efficacy of the experimental biopesticide DWR2009 in liquid and bait 

form (by coating wheat bran with the pathogen) using ultra-ultra low volume RAATs 

(involves a timing device and ULV nozzles) and a 10 acre plot. ATV-mounted liquid and 

bait spreaders will be utilized to apply DWR2009. Specimens will be periodically 

collected to observe mortality and sporulation for a duration of time to determine 

efficacy.

Study 6: Evaluate efficacy of the experimental, non-traditional pesticide LinOilEx 

(Formulation 103). A micro-FAASSTT (airbrush system mounted on a 5 gallon bucket) 

will be utilized to apply varying dose levels in order to compare efficacy, starting at the 

base rate of 6.64 ml/cage. A grasshopper species of local abundance will be placed into 
15

replicated microplot cages and sprayed directly. Mortality will be then be observed for a 

duration of time to determine efficacy.

III. Affected Environment

A. Description of Affected Environment

This EA covers the State of Wyoming. Additionally, APHIS recognizes that concerns 

outside this area could necessitate protection buffers that extend into this area. 

The size of this region is approximately 97,914 square miles (62,664,960 acres). The 

total relief is 10,690 feet and ranges from 3,114 feet to 13,804 feet at Gannett Peak. 

Grasshopper and Mormon cricket treatments occur primarily between 3,640 feet and 

7,500 feet in this region. Pine forests dominate the higher elevation. No treatments are 

anticipated in these forested areas. Annual precipitation in the primary area of concern 

ranges from 6 inches to 22 inches. Precipitation is higher in the mountains. 

Temperatures can be extremely variable at any location. Summer temperatures in the 

90's and low 100's are common in the lower elevations. Winter low temperatures are 

often well below 0 degrees Fahrenheit (oF). The yearly mean temperatures for the region 

are 40 oF to 48 oF.

Croplands are concentrated along major rivers where irrigation is possible. Less than 3 

percent of the region is cultivated. The major crops are:

CROP ACRES CROP ACRES

Alfalfa 530,000 Corn 110,000

Other Hay 550,000 Oats 23,000

Wheat 145,000 Sugar Beets 31,300

Barley 100,000 Dry Beans 32,000

(Acreage figures are from National Agricultural Statistics Service, Wyoming Agriculture 

Statistics, 2015 Crop Acres Planted). Damage to these croplands is expected when 

migrating bands of Mormon crickets and grasshoppers enter these fields.

Information on the species composition of grasshoppers is available from USDA APHIS 

PPQ in Cheyenne, Wyoming through the Wyoming Grasshopper Information System. 

The species of major economic importance are: Ageneotettix deorum, Amphitornus 

coloradus, Anabrus simplex, Aulocara elliotti, Aulocara femoratum, Camnula pellucida, 

Cordillacris crenulata, Cordillacris occipitalis, Melanoplus bivittatus, M. differentialis, 

M. femurrubrum, M. infantilis, M. occidentalis, M. sanguinipes, Phlibostroma 

quadrimaculatum, Phoetaliotes nebrascensis, and Trachyrhachys kiowa. Approximately 

96 other lesser important species are represented in surveys from this region. These 96

species may become economic pests if part of a high density species complex. Warm, 

dry weather is generally the most favorable for high populations, and severe loss of 

forage most often occurs in conjunction with drought.
16

The major population centers are in the towns of Cheyenne and Casper. Smaller towns 

are located throughout the region. The total population is approximately 563,626 (2010 

census figure). 

Major recreational areas in this region include eleven State parks and eight National 

Forests. The top five most visited State Parks in Wyoming are Hot Springs State Park 

with 1,821,006 visitors, Glendo State Park with 300,801 visitors, Bear River State Park 

with 261,540 visitors, Sinks Canyon State Park with 212,019 visitors and Keyhole State 

Park with 187,324 visitors in 2014 (Wyoming State Parks Visitor Use Program, 2016). 

Statistics for 2015 are pending publication. Wyoming’s eight National Forests total 9.7 

million acres (National Forest Service, 2016). The roads through the region are a major 

thoroughfare for tourist traffic to and from Wyoming’s two National Parks, two National 

Monuments and over twenty National Historic Sites and Trails. Yellowstone National 

Park recorded 4,095,317 visitors for 2015 alone and has recorded between 2.8 million 

and 3.6 million visitors per year since 2000 (Yellowstone National Park Visitor Statistics, 

2016). 

Domestic honeybee yards are found throughout Wyoming. Approximately 268 hobbyist 

(10 hives or less) apiarists and 163 general commercial apiarists make up the total 

registered 431 apiarists who operate 48,000 bee yards and over 100 million bee hives in 

Wyoming. Most of these colonies seasonally migrate to California to pollinate the 

almond orchards. Wyoming also has a hearty alfalfa seed production industry and alfalfa 

leafcutter bees are commonly used in some areas covered by this EA. Site specific 

locations can be found through apiary registrations at the Wyoming Department of 

Agriculture or checking with alfalfa seed producers in the case of leafcutter bees (WDA, 

2015).

Many species of big game (antelope, mule deer, whitetail deer, elk, and others) and 

smaller animals (rabbits, squirrels, muskrats, beavers, minks, weasels, badgers, coyotes 

and foxes) range within the varied habitats. Livestock ponds, streams and reservoirs 

within the proposed treatment area provide a nesting and breeding habitat for waterfowl. 

Many nongame birds migrate through or nest in the region. Golden eagles, peregrine 

falcons and other raptors nest within the region and game birds (ringed necked pheasant, 

greater sage-grouse, wild turkey, Hungarian partridge, chukar and dove) are present. 

Recreational hunting is very important to the local economy.

B. Other Considerations

1. Human Health

The 2002 EIS and 2019 EIS contains detailed hazard, exposure, and risk analyses for the 

chemicals available to APHIS. Impacts to workers and the general public were analyzed 

for all possible routes of exposure (dermal, oral, inhalation) under a range of conditions 

designed to overestimate risk. The operational procedures and spraying conditions 

examined in those analyses conform to those expected for operations. The following 

discussion summarizes the hazards, potential exposure, and risk to workers and the 

general public for operations in Wyoming. Operational procedures identified in 
17

Appendix 1 would be required in all cases and further mitigation measures are identified 

in this section, as appropriate.

No treatment will occur over congested areas, recreation areas, or schools and if 

appropriate, a buffer zone will be enacted and enforced. Refer to the Operational 

Procedures for ground and aerial treatments listed in Appendix 1. Further Treatment 

information can be found in the Grasshopper Guidebook Provisional online at 

https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-diseaseprograms/pests-and-diseases/grasshopper-mormoncricket/ct_grasshopper_mormon_cricket.

Groundwater wells are a major source of domestic water supplies. Groundwater and 

surface water are the major rural and livestock water source. No impact is anticipated. 

Strict adherence to label requirements and USDA treatment guidelines (Appendix 1) will 

be followed regarding treatments bordering open surface waters.

Malathion and carbaryl are cholinesterase inhibitors. Cholinesterases (including AChE) 

are enzymes that function at the nerve synapse. The nerve synapse is the point where 

information in the form of electrical impulses is relayed or transmitted by chemical 

messengers (called transmitters) from one nerve cell to another. Cholinesterase then 

inactivates or destroys the transmitter chemical (like acetylcholine) after it completes its 

job, otherwise the transmitter would continue indefinitely and precise control of the 

enervated tissue (muscle or organ) would be lost. Refer to the 2015 guidelines 

(Appendix 1) for further information on mitigating exposure to cholinesterase inhibitors. 

No human health effects are likely from exposure to diflubenzuron if it is used according 

to label instructions. A human exposure assessment was done in detail for diflubenzuron 

and can be found in APHIS’s “Chemical Risk Assessment for Diflubenzuron Use in 

Grasshopper Cooperative Control Program”.

2. Non-target Species

Sensitive non-target species within the area include plants, terrestrial vertebrates and 

invertebrates, bats, resident and migratory birds, biocontrol agents, pollinators, aquatic 

organisms, and Federal and State listed threatened and endangered species. APHIS will 

use an Integrated Pest Management (IPM) approach to ensure non-target effects are 

reduced. APHIS will also consult with local agency officials to determine appropriate 

protective measures. Appropriate protective measures will be considered within an IPM 

framework. These strategies may include but are not limited to chemical selection, 

reduced rates, reduced coverage areas, buffer zones, timing restrictions and 

environmental monitoring. If such a request occurs and the grasshopper or Mormon 

cricket management option selected poses a clear threat to any of these species, APHIS 

will confer with the land managers, the U.S. Fish and Wildlife Service and/or WGFD 

personnel to agree on protective measures.
18

a) Threatened and Endangered Species and Sensitive

Species of Concern

The following are federally listed threatened and endangered species that reside in 

Wyoming.

FEDERALLY LISTED THREATENED AND ENDANGERED SPECIES:

Animals Latin Name Listed Status

Northern Long-Eared Bat Myotis septentrionalis Threatened

Grizzly Bear Ursus arctos horribilis Threatened

Humpback Chub Gila cypha Endangered

Yellow-Billed Cuckoo Coccyzus americanus Threatened

Kendall Warm Springs Dace Rhinichthys osculus thermalis Endangered 

Black-Footed Ferret Mustela nigripes Endangered / Experimental

Canada Lynx Lynx canadensis Threatened

Preble’s Meadow Jumping Mouse Zapus hudsonius preblei Threatened

Colorado Pikeminnow Ptychocheilus lucius Endangered

Piping Plover Charadrius melodus Threatened / Endangered

Least Tern Sterna antillarum Endangered

Wyoming Toad Anaxyrus baxteri Endangered

Western Glacier Stonefly Zapada glacier Threatened

Plants Latin Name Listed Status

Ute Ladies’-Tresses Spiranthes diluvialis Threatened

Western Prairie Fringed Orchid Platanthera praeclara Threatened

Blowout Penstemon Penstemon haydenii Endangered 

Desert Yellowhead Yermo xanthocephalus Threatened

A summary of species determinations and impact minimization measures can be found in 

Appendix 3. In the absence of a recent national biological opinion, local Section 7

consultations are conducted yearly with USFWS to mitigate impacts that grasshopper 

suppression programs may have on listed threatened and endangered species. These 

correspondences can be found in Appendix 2.

b) Greater Sage-Grouse (Centrocercus urophasianus)

The Wyoming Game and Fish Department (WGFD) and Bureau of Land Management 

(BLM) have indicated concern regarding the impacts of a grasshopper suppression 

program on greater sage-grouse, hereafter referred to as sage-grouse. Concerns to sagegrouse include the toxicity effects of the chemicals in question, the effects to the food 

base of the sage-grouse, and the physical disturbance factors related to a grasshopper 

suppression program. Wyoming historically supports larger populations of sage-grouse 

than other states due to the approximately 50 % of land area that is composed of 

sagebrush habitats (Patterson 1952). 
19

Concern and protection of sage-grouse in Wyoming has been a priority for leaders in 

Wyoming for many years and has been expressed through the Governor’s Executive 

Orders. Throughout the years, Executive Orders 2008-2, 2010-4, 2011-5, 2013-3, 2015-4, 

and 2017-2 have protected sage-grouse and their habitat and developed management

strategies. The Governor’s Sage-Grouse Implementation Team developed the sagegrouse core population area concept in order to protect critical habitat from further 

degradation. Executive Order 2019-3 supersedes all previous executive orders. The BLM 

has issued Instruction Memorandum WY 2012-019 entitled Greater Sage-Grouse Habitat 

Management Policy on Wyoming BLM Administered Public Lands Including the Federal 

Mineral Estate. 

Sage-grouse as a species of concern was addressed in the 2002 EIS and in the updated 

2019 EIS. While it is clear that diflubenzuron poses less direct toxicity to greater sagegrouse than both carbaryl and malathion, toxicities were analyzed in the risk assessment 

and concluded that grasshopper suppression RAATs alternatives would not directly affect 

greater sage-grouse for any of the proposed insecticides.

The effect of grasshopper suppression programs to the food base of the greater sagegrouse can be important during the early brood rearing timing of the sage-grouse life 

cycle. Study results indicate that sage-grouse chicks require insects for survival until 

about three weeks of age (Johnson, May 1987). For most of Wyoming, this timing 

coincides with the earliest likely timing of grasshopper suppression programs. In order to 

limit the effects to the food base of the greater sage-grouse APHIS PPQ will utilize 

grasshopper suppression RAATs alternatives within greater sage-grouse core population 

areas. By using the RAATs method, effects to non-target insects and grasshoppers will 

be reduced. The Governor’s Executive Order 2019-3 specifically lists Grasshopper / 

Mormon cricket control following Reduced Agent-Area Treatments (RAATs) protocols 

as a de-minimis (exempt) activity under Appendix G, “De-minimis” Activities. 

In extreme cases grasshopper infestations may be so damaging that crucial sage-grouse 

habitat is compromised. These areas may not be apparent in time to use diflubenzuron 

and a faster knockdown may be required to protect the habitat. For these situations 

APHIS reserves the ability to use carbaryl and malathion in greater sage-grouse core 

population areas. If treatments are late enough in the season that diflubenzuron is 

deemed ineffective then it is also most likely that sage-grouse chicks will be mature 

enough that they will have adjusted their diet to a mixture of forbs and sage brush versus 

insects only. Situations that require the use of carbaryl or malathion within sage-grouse 

core population areas will be considered on a case by case situation only with input from 

the land manager, landowner and WGFD. 

In 2015 the USFWS requested data from 11 western states, including Wyoming, to aide 

in the ESA listing decision of the sage-grouse. The data included sage-grouse 

populations’ status, trends and numbers, habitat status and trends, hunting and other uses, 

disease and predation, impacts from pesticides, contaminants, recreational activities, and 

any literature pertinent to the USFWS status review. The compiled data demonstrated 

Wyoming’s commitment and assurance to sage-grouse conservation and the 
20

determination of the western states to logistically and financially conserve sage-grouse 

habitat and protect the sage-grouse species. Reviews of the complied data lead to the 

United States Department of the Interior determining that listing the greater sage-grouse 

range wide as a threatened or endangered species was precluded making it a candidate 

species which will not receive statutory protection under the ESA. Sage-grouse are no 

longer considered a candidate species by the U.S. Fish and Wildlife Service (50 FR 

24292). In the WGFD 2017 State Wildlife Action Plan sage-grouse are identified as a 

Tier II SGCN (Tier II is moderate priority). If grasshopper suppression treatments are 

requested in sage-grouse core population areas, APHIS PPQ will consider additional 

conditions and mitigation measures outlined in the request. Discussions with local 

entities such as WGFD and BLM will also occur to determine appropriate steps to 

suppress grasshopper populations and protect sage-grouse populations and habitat ranges.

c) Species of special concern to the Wyoming Game and

Fish Department 

The WGFD lists Species of Greatest Conservation Need (SGCN). This list may be 

found in State Wildlife Action Plan, 2017, which can be found at 

https://wgfd.wyo.gov/Habitat/Habitat-Plans/Wyoming-State-Wildlife-Action-Plan. 

WGFD has specific concerns regarding nongame birds and bats with respect to 

grasshopper suppression programs.

i. Nongame birds

The following species appear on the SGCN list and the Wyoming Partners in Flight 

Priority Species list, and may be negatively affected by grasshopper control in areas 

where they nest and forage: burrowing owl, short-eared owl, Brewer’s sparrow, sage 

sparrow, Baird’s sparrow, McCown’s longspur, loggerhead shrike, sage thrasher, vesper 

sparrow, lark sparrow, lark bunting, dickcissel, bobolink, black-billed cuckoo, black 

throated gray warbler, Clark’s nutcracker, MacGillivray’s warbler, Scott’s oriole, 

Virginia’s warbler, Bewick’s wren, canyon wren and snowy plover. In particular, the 

following species consume large amounts of grasshoppers and/or Mormon Crickets; 

therefore, the impact of grasshopper control on these species is likely to negatively affect 

both adult and young birds during the nesting season: McCown’s longspur, loggerhead 

shrike, sage thrasher, lark bunting, black-billed cuckoo, Virginia’s warbler, Bewick’s 

wren, mountain plover and snowy plover. APHIS would use RAATs methodologies for 

treatments in most cases, as RAATs with diflubenzuron is the preferred methodology. 

This method is expected to result in 80 to 95% control, which is approximately 5 to 15% 

lower mortality than with a conventional (higher rate, blanket coverage) treatment 

(University of Wyoming, 2010). RAATs methods are expected to leave adequate prey 

base for insectivorous species. At no time will APHIS strive to eradicate grasshopper 

populations.

ii. Bats

In previous years, the WGFD has raised concerns about possible impacts of this program 

on spotted bats. The spotted bat is a nocturnal feeder on flying insects primarily around 

desert water holes. The bat and its food source are protected by the buffers associated 
21

with water. Additional protective measures, such as the use of bait or RAATs, will be 

negotiated with the WGFD if proposed pesticide applications directly conflict with sites 

having recent spotted bat activity.

d) Bald and Golden Eagle Protection Act 

The Eagle Act (16 U.S.C. 668-668c), enacted in 1940, and amended several times since 

then, prohibits anyone, without a permit issued by the Secretary of the Interior, from 

“taking” bald eagles, including their parts, nests, or eggs. The Act provides criminal and 

civil penalties for persons who “take, possess, sell, purchase, barter, offer to sell, 

purchase or barter, transport, export or import, at any time or any manner, any bald eagle 

... [or any golden eagle], alive or dead, or any part, nest, or egg thereof.” The Act defines 

“take” as “pursue, shoot, shoot at, poison, wound, kill, capture, trap, collect, molest or 

disturb.” “Disturb’’ means: "to agitate or bother a bald or golden eagle to a degree that 

causes, or is likely to cause, based on the best scientific information available, 1) injury to 

an eagle, 2) a decrease in its productivity, by substantially interfering with normal 

breeding, feeding, or sheltering behavior, or 3) nest abandonment, by substantially 

interfering with normal breeding, feeding, or sheltering behavior." In addition to 

immediate impacts, this definition also covers impacts that result from human-induced 

alterations initiated around a previously used nest site during a time when eagles are not 

present, if, upon the eagles return, such alterations agitate or bother an eagle to a degree 

that injures an eagle or substantially interferes with normal breeding, feeding, or 

sheltering habits and causes, or is likely to cause, a loss of productivity or nest 

abandonment.

As listed in the National Bald Eagle Management Guidelines (USFWS, May 2007) the 

following mitigation measures will be followed when practical:

“Category G. Helicopters and fixed-wing aircraft. Except for authorized biologists 

trained in survey techniques, avoid operating aircraft within 1,000 feet of the nest 

during the breeding season, except where eagles have demonstrated tolerance for 

such activity. In addition, Category A (Agriculture) and Category D (Off Road 

Vehicle Use) both provide the same guidance for use of ATV's or trucks: No 

buffer is necessary around nest sites outside the breeding season. During the 

breeding season, do not operate off-road vehicles within 330 feet of the nest. In 

open areas, where there is increased visibility and exposure to noise, this distance 

should be extended to 660 feet.”

Most bald eagles’ nest close to their food source, typically waterways, by policy and label 

restrictions APHIS will not conduct suppression activities within 500 feet of water bodies 

providing some inherent protection for Bald Eagles. 

e) Aquatic Species not previously listed

The malathion label warns of its toxicity to fish, shrimp, and crabs and prohibits its use 

over water. EPA lists carbaryl and malathion as pesticides that may affect endangered 

aquatic species (EPA, 1986).
22

Diflubenzuron is the main ingredient in Dimilin® 2L, Cavalier 2L and Unforgiven. 

These chemical products are listed as Restricted Use Pesticides due to toxicity to aquatic 

invertebrate animals including insects and it cannot be applied directly to water or to 

areas where surface water is present.

Important game fish in the region include: walleye, sauger, cutthroat trout, brown trout, 

rainbow trout, brook trout and lake trout. 

Programmatic protection for federally listed endangered and threatened species of aquatic 

animals is covered in the 2002 EIS and 2019 EIS, Biological Assessments, and the 

Biological Opinions. These procedures will ensure protection of sensitive aquatic species 

from any adverse effects caused by grasshopper control.

f) Bees

 i. Domestic Honey Bees (Apis mellifera)

Beekeepers are given notice when definitive treatment areas are identified. Treatment 

block maps will be available for beekeeper review at the County offices of the Weed and 

Pest Districts. Beekeepers will be advised to move their bees at least two miles from the 

spray block boundaries. In all cases when using malathion or carbaryl where beekeepers 

fail to move or otherwise protect their bees, a two mile buffer zone will be observed 

around the bee yard. The above procedures will ensure that there will be no significant 

impact on domestic bee production.

 ii. Alfalfa Leafcutter Bees (Megachile rotundata)

Alfalfa leafcutter bees are managed for pollination of alfalfa in the area. The areas with 

these bees are mostly centered at Basin, Burlington, Emblem, Powell, Byron, Lovell and 

Riverton. Notification is on a case-by-case basis. Beekeepers will be advised to move 

their bees at least four miles from the spray block boundaries. In all cases when using 

malathion or carbaryl where beekeepers fail to move or otherwise protect their bees, a 

four mile buffer zone will be observed around the bee yard. The above procedures will 

ensure that there will be no significant impact on alfalfa leafcutter bee activity.

g) Wildlife Habitat Reservations and Wilderness Areas

The WGFD operates 39 Wildlife Habitat Management Units in Wyoming. These can be 

located on the web at https://wgfd.wyo.gov/accessto/whmas.asp. If a request for 

treatment involves any of these lands, APHIS will negotiate locally with the habitat 

biologist located at the nearest Game and Fish regional office for any protective measures 

necessary, in addition to the operation procedures.

h) Bureau of Land Management Wilderness Study Areas

In Wyoming there are 43 Bureau of Land Management (BLM) administered Wilderness 

Study Areas (WSA), encompassing 588,150 acres. These can be located on the web at 

https://www.blm.gov/programs/national-conservation-lands/wyoming. These WSA’s are 

managed under BLM’s Interim Management Policy (IMP).
23

The objective of the IMP is to continue resource uses within the WSA’s in a manner that 

maintains the area's suitability for preservation as wilderness until Congress either 

designates these lands as wilderness or releases them for other purposes. 

Handbook H-8550-1 (Interim Management Policy for Lands under Wilderness Review) 

provides guidance regarding how BLM will manage the WSA’s. H-8550-1 does provide 

for insect and disease control by chemical or biological means under certain conditions as 

discussed in Chapter 3, Section D Rangeland Management, 4 e.

Because of the special requirements found in H-8550-1, including NEPA related 

requirements, before conducting any Grasshopper and Mormon cricket project involving 

a WSA, the BLM Field Office administering the specific WSA will be consulted with 

and involved in the project.

i) Migratory Birds

In accordance with various environmental statutes, APHIS routinely conducts programs 

in a manner that minimizes impact to the environment, including any impact to migratory 

birds. In January 2001, President Clinton signed Executive Order (EO) number 13186 to 

ensure that all government programs protect migratory birds to the extent practicable. 

APHIS will support the conservation intent of the migratory bird conventions by 

integrating bird conservation principles, measures, and practices into agency activities 

and by avoiding or minimizing, to the extent practicable, adverse impacts on migratory 

bird resources when conducting agency actions. 

j) Protective Mitigation Measures of Above Species

Protective mitigation measures that may be taken by APHIS in the grasshopper treatment 

areas covered by this EA may include, but is not limited to, buffer zones and/or skip 

swaths. It is important to note that treatment goals are to reduce grasshopper populations 

to an economic threshold, not eradication. At no time will APHIS strive to reduce 

populations below levels encountered in non-outbreak years. This will help ensure 

grasshopper populations sufficient to provide food sources and biodiversity for species of 

concern.

If after specific program boundaries have been set and if it has been determined by Fish 

and Wildlife Services or the land manager that species of concern are within the specific 

area, mitigation measures as described in Appendix 3 or site specific documentation will 

be followed.

3. Socioeconomic Issues

The possible treatment areas are subject to reoccurring drought. A combination of 

drought and grasshopper damage causes economic stress to landowners and permittees.

The control of grasshoppers and Mormon crickets in this area would have beneficial 

economic impacts to local landowners (or permittees). The forage not utilized by 

grasshoppers will be available for wildlife consumption, livestock consumption, and 

harvesting. This will allow greater livestock grazing, decreased needs for supplemental 
24

feed, and increased monetary returns. The control of migrating bands of Mormon 

crickets is most important in protection of crops but if populations are extreme, damage 

to rangeland forage will occur.

4. Cultural Resources and Events

To ensure that historical sites, monuments, buildings, artifacts or known areas of cultural 

events and/or observances of special concern are not adversely affected by program 

treatments, APHIS will confer locally with Tribes, state and federal land managers on 

proposed treatment areas. 

In previous years, BLM has expressed concerns regarding the effect of pesticide 

applications on cation ratio dating techniques of pictographs and petroglyphs. There is 

presently no information on this subject. Until such information is available, USDA 

APHIS will confer with BLM on a local level to protect known sites on BLM managed 

lands. 

Where tribal lands are involved, APHIS will confer locally with Tribal Officials and with 

the BIA office to ensure that the timing and location of planned program treatments do 

not coincide or conflict with cultural events and/or observances on Tribal and/or allotted 

lands. APHIS will confer locally with Tribal Officials and with the BIA office on 

possible cultural impacts of proposed grasshopper/Mormon cricket treatment where 

native plant gathering areas on tribal land are identified to APHIS.

5. Special Considerations for Certain Populations

a) Executive Order Number 12898, Federal Actions to Address Environmental

Justice in Minority Populations and Low-Income Populations

Executive Order (EO) number 12898, Federal Actions to Address Environmental Justice 

in Minority Populations and Low-Income Populations, was signed by President Clinton 

on February 11, 1994 (59 Federal Register (FR) 7269). This EO requires each Federal 

agency to make achieving environmental justice part of its mission by identifying and 

addressing, as appropriate, disproportionately high and adverse human health or 

environmental effects of its programs, policies, and activities on minority populations and 

low-income populations. Consistent with this EO, APHIS will consider the potential for 

disproportionately high and adverse human health or environmental effects on minority 

populations and low-income populations for any of its actions related to grasshopper 

suppression programs. 

Consistent with EO number 12898, Federal Actions to Address Environmental Justice in 

Minority Populations and Low Income Populations, APHIS considered the potential for 

disproportionately high and adverse human health or environmental effects from the 

proposed treatment is minimal and is not expected to have disproportionate adverse 

effects to any minority or low income populations.
25

b) Executive Order Number 13045, Protection of Children from Environmental 

Health Risks and Safety Risks

The increased scientific knowledge about the environmental health risks and safety risks 

associated with hazardous substance exposures to children and recognition of these issues 

in Congress and Federal agencies brought about legislation and other requirements to 

protect the health and safety of children. On April 21, 1997, President Clinton signed EO

number 13045, Protection of Children from Environmental Health Risks and Safety Risks 

(62 FR 19885). This EO requires each Federal agency, consistent with its mission, to 

identify and assess environmental health risks and safety risks that may 

disproportionately affect children and to ensure that its policies, programs, activities, and 

standards address those risks. APHIS has developed agency guidance for its programs to 

follow to ensure the protection of children (USDA, APHIS, 1999). 

The human health risk assessment for the 2002 EIS analyzed the effects of exposure to 

children from three insecticides. The 2019 EIS updates and replaces the 2002 EIS. Based 

on review of all four insecticides and their use in the grasshopper program, the risk 

assessment concluded that the likelihood of children being exposed to insecticides is very 

slight and that no disproportionate adverse effects to children are anticipated over the 

negligible effects to the general population. Treatments are primarily conducted on open 

rangelands where children would not be expected to be present during treatment, or enter 

should there be any restricted entry period after treatment. No treatment will occur over 

congested areas or schools and if appropriate, a buffer zone will be enacted and enforced. 

Impacts on children will be minimized by the implementation of the treatment guidelines 

as further described in Appendix 1: 

 Aerial Broadcast Applications of Liquid Insecticides

• Notify all residents in treatment areas, or their designated representatives, prior to 

proposed operations. Advise them of the control method to be used, the proposed method 

of application, and precautions to be taken (e.g., advise parents to keep children and pets 

indoors during ULV treatment). Refer to label recommendations related to restricted 

entry period.

• No treatments will occur over congested urban areas. For all flights over congested 

areas, the contractor must submit a plan to the appropriate Federal Aviation 

Administration District Office and this office must approve of the plan; a letter of 

authorization signed by city or town authorities must accompany each plan. Whenever 

possible, plan aerial ferrying and turnaround routes to avoid flights over congested areas, 

bodies of water, and other sensitive areas that are not to be treated.

 Aerial Application of Dry Insecticidal Bait

• Do not apply within 500 feet of any school or recreational facility.

 Ultra-Low-Volume Aerial Application of Liquid Insecticides

• Do not spray while school buses are operating in the treatment area.

• Do not apply within 500 feet of any school or recreational facility.
26

IV. Environmental Consequences

Each alternative described in this EA potentially has adverse environmental effects. The 

general environmental impacts of each alternative are discussed in detail in the 2002 and 

2019 EIS. The specific impacts of the alternatives are highly dependent upon the 

particular action and location of infestation. The principal concerns associated with the 

alternatives are: (1) the potential effects of insecticides on human health (including 

subpopulations that might be at increased risk); and (2) impacts of insecticides on nontarget organisms (including threatened and endangered species). 

APHIS has written human health and ecological risk assessments (HHERAs) to assess 

the insecticides and use patterns that are specific to the program. The risk assessments 

provide an in-depth technical analysis of the potential impacts of each insecticide to 

human health; and non-target fish and wildlife along with its environmental fate in soil, 

air, and water. The assessments rely on data required by the USEPA for pesticide product 

registrations, as well as peer-reviewed and other published literature. The HHERAs are 

heavily referenced in this final EA. These Environmental Documents can be found at the 

following website: http://www.aphis.usda.gov/plant-health/grasshopper. 

A. Environmental Consequences of the Alternatives

Environmental consequences of the alternatives are discussed in this section.

1. No Suppression Program Alternative

Under this alternative, APHIS would not organize or fund a program to suppress 

grasshoppers. If APHIS does not participate in any grasshopper suppression program, 

Federal land management agencies, State agriculture departments, local governments, 

private groups or individuals, may not effectively combat outbreaks in a coordinated 

effort. Without the technical assistance and coordination that APHIS provides during 

grasshopper outbreaks, the uncoordinated programs could use insecticides that APHIS 

considers too environmentally harsh. Multiple treatments and excessive amount of 

insecticide could be applied in efforts to suppress or even locally eradicate grasshopper 

populations. There are approximately 100 pesticide products registered by USEPA for 

use on rangelands and against grasshoppers (Purdue University, 2018). It is not possible 

to accurately predict the environmental consequences of the No Suppression alternative 

because the type and amount of insecticides that could be used in this scenario are 

unknown. However, the environmental impacts could be much greater than under the 

APHIS led suppression program alternative due to lack of treatment knowledge or 

coordination among the groups.

The potential environmental impacts from the No Suppression alternative, where other 

agencies and land managers do not control outbreaks, stem primarily from grasshoppers 

consuming vast amounts of vegetation in rangelands and surrounding areas. 

Grasshoppers are general feeders, eating grasses and forbs first and often moving to 

cultivated crops. High grasshopper density of one or several species and the resulting 

defoliation may reach an economic threshold where the damage caused by grasshoppers 

exceeds the cost of controlling the grasshoppers. Researchers determined that during 

typical grasshopper infestation years, approximately 20% of forage rangeland is removed, 
27

valued at a dollar adjusted amount of $900 million. This value represents 32 to 63% of 

the total value of rangeland across the western states (Rashford et al., 2012). Other 

market and non-market values such as carbon sequestration, general ecosystem services, 

and recreational use may also be impacted by pest outbreaks in rangeland.

Vegetation damage during large-scale grasshopper outbreaks may be so severe that 

grasses and forbs are destroyed, resulting in poor or impaired plant growth for several 

years. Grasshoppers in unsuppressed outbreaks would consume agricultural and 

nonagricultural plants. Rare, threatened or endangered plants may be consumed during 

critical times of development such as seed production, and loss of important plant 

species, or seed production may lead to reduced diversity of rangeland habitats, 

potentially creating opportunities for the expansion of invasive and exotic weeds 

(Lockwood and Latchininsky, 2000). When grasshoppers consume plant cover, soil is 

more susceptible to the drying effects of the sun, making plant roots less capable of 

holding soil in place. Soil damage results in erosion and disruption of nutrient cycling, 

water infiltration, seed germination, and other ecological processes which are important 

components of rangeland ecosystems (Latchininsky et al., 2011).

When the density of grasshoppers reaches significantly high levels, grasshoppers begin to 

compete with livestock for food by reducing available forage (Wakeland and Shull, 1936; 

Belovsky, 2000; Pfadt, 2002; Branson et al., 2006; Bradshaw et al., 2018). Ranchers 

could offset some of the costs by leasing rangeland in another area and relocating their 

livestock, finding other means to feed their animals by purchasing hay or grain, or selling 

their livestock. Ranchers could also incur economic losses from personal attempts to 

control grasshopper damage. Local communities could see adverse economic impacts to 

the entire area. Grasshoppers that infest rangeland could move to surrounding croplands. 

Farmers could incur economic losses from attempts to chemically control grasshopper 

populations or due to the loss of their crops. The general public could see an increase in 

the cost of meat, crops, and their byproducts.

2. Insecticide Applications at Conventional Rates or Reduced Agent Area 

Treatments with Adaptive Management Strategy

Under Alternative 2, APHIS would participate in grasshopper programs with the option 

of using one of the insecticides malathion, carbaryl, or diflubenzuron, depending upon 

the various factors related to the grasshopper outbreak and the site-specific 

characteristics. The use of an insecticide would typically occur at half the conventional 

application rates following the RAATs strategy. APHIS would apply a single treatment to

affected rangeland areas in an attempt to suppress grasshopper outbreak populations by a 

range of 35 to 98 %, depending upon the insecticide used. 

a) Malathion

Malathion is a broad-spectrum organophosphate insecticide widely used in agriculture on 

various food and feed crops, homeowner yards, ornamental nursery stock, building 

perimeters, pastures and rangeland, and regional pest eradication programs. The 

chemical’s mode of action is through AChE inhibition, which disrupts nervous system 

function. While these effects are desired in controlling insects, they can have undesirable 
28

impacts to non-target organisms that are exposed to malathion. The grasshopper program 

currently uses the malathion end-use product Fyfanon® ULV AG, applied as a spray by 

ground or air.

Volatility is not expected to be a major pathway of exposure based on the low vapor 

pressure and Henry’s Law constant that have been reported for malathion. The 

atmospheric vapor phase half-life of malathion is five hours (NIH, 2009b). Malathion’s 

half-life in pond, lake, river, and other natural waters varied from 0.5 days to 10 days, 

depending on pH (Guerrant et al., 1970), persisting longer in acidic aquatic environments. 

The reported half-life in water and sediment for the anaerobic aquatic metabolism study 

was 2.5 days at a range of pH values from 7.8 to 8.7 (USEPA, 2006). The persistence of 

malathion in soils depends primarily on microorganism activity, pH, and organic matter 

content. The persistence of malathion is decreased with microbial activity, moisture, and 

high pH (USEPA, 2016a) and the half-life of malathion in natural soil varies from two 

hours (Miles and Takashima, 1991) to 11 days (Neary, 1985; USEPA, 2006). 

Malathion and associated degradants, in general, are soluble and do not adsorb strongly 

to soils (USEPA, 2000a). Inorganic degradation of malathion may be more important in 

soils that are relatively dry, alkaline, and low in organic content, such as those that 

predominate in the western program areas. Adsorption to organic matter and rapid 

degradation make it unlikely that detectable quantities of malathion would leach to 

groundwater (LaFleur, 1979). Malathion degradation products also have short half-lives. 

Malaoxon, the major malathion degradation product of toxicological concern, has halflives less than one day in a variety of soil types (USEPA, 2016a). The half-life of 

malathion on foliage has been shown to range from one to six days (El-Refai and 

Hopkins, 1972; Nigg, 1986; Matsumara, 1985; USDA FS, 2008).

While livestock and horses may graze on rangeland the same day that the land is treated 

with malathion, the products used by the grasshopper program are labeled with rates and 

treatment intervals that are meant to protect livestock. Tolerances are set based on the 

amount of malathion that is allowed in cattle fat (4 ppm), meat (4 ppm), and meat 

byproducts (4 ppm) (40 CFR Parts 180.111). The grasshopper program would treat at 

application rates indicated on product labels or lower, which would ensure approved 

residue levels. In addition, the program would make only one application a year.

USEPA found malathion moderately toxic to birds on a chronic basis, slightly toxic to 

mammals through dietary exposure, and acutely toxic to aquatic species (including 

freshwater as well as estuarine and marine species) (USEPA, 2000b, 2016b). Toxicity to 

aquatic vertebrates such as fish and larval amphibians, and aquatic invertebrates is 

variable based on test species and conditions. The data available on impacts to fish from 

malathion suggest effects could occur at levels above those expected from program 

applications. Consumption of contaminated prey is not expected to be a significant 

pathway of exposure for aquatic species based on expected residues and malathion’s BCF 

(USEPA, 2016a; USDA APHIS, 2018d). Indirect effects to fish from impacts of 

malathion applications to aquatic plants are not expected (USDA APHIS, 2018d).
29

USEPA considers malathion highly toxic to bees if exposed to direct treatment on 

blooming crops or weeds. The Fyfanon® ULV AG label indicates not to apply product or 

allow it to drift to blooming crops or weeds while bees are actively visiting the treatment 

area (USEPA, 2012a). Toxicity to other terrestrial invertebrates is variable based on the 

test organism and test conditions however malathion is considered toxic to most 

terrestrial invertebrates (USEPA, 2016b).

Indirect risks to mammals resulting from the loss of plants that serve as a food source 

would also be low due to the low phytotoxicity of malathion. The other possible indirect 

effect that should be considered is loss of invertebrate prey for those mammals that 

depend on insects and other invertebrates as a food source. Insects have a wide variety of 

sensitivities to malathion and a complete loss of invertebrates from a treated area is not 

expected because of low program rates and application techniques. In addition, the aerial 

and ground application buffers and untreated swaths provide refuge for invertebrates that 

serve as prey for insectivorous mammals and would expedite repopulation of areas that 

may have been treated.

APHIS expects that direct avian acute and chronic effects would be minimal for most 

species (USDA APHIS, 2018d). The preferred use of RAATs during application reduces 

these risks by reducing residues on treated food items and reducing the probability that 

they will only feed on contaminated food items. In addition, malathion degrades quickly 

in the environment and residues on food items are not expected to persist. Indirect effects 

on birds from the loss of habitat and food items are not expected because of malathion’s 

low toxicity to plants and the implementation of RAATs that would reduce the potential 

impacts to invertebrates that serve as prey for avian species. Several field studies did not 

find significant indirect effects of malathion applications on avian fecundity (Dinkins et 

al., 2002; George et al., 1995; Howe, 1993; Howe et al., 1996; Norelius and Lockwood, 

1999; Pascual, 1994).

Available toxicity data demonstrates that amphibians are less sensitive to malathion than 

fish. Program malathion residues are more than 560 times below the most sensitive acute 

toxicity value for amphibians. Sublethal effects, such as developmental delays, reduced 

food consumption and body weight, and teratogenesis (developmental defects that occur 

during embryonic or fetal growth), have been observed at levels well above those 

assessed from the program’s use of malathion (USDA APHIS, 2018d). Program 

protection measures for aquatic water bodies and the available toxicity data for fish, 

aquatic invertebrates, and plants suggest low indirect risks related to reductions in habitat 

or aquatic prey items from malathion treatments.

Available data on malathion reptile toxicity suggest that, with the use of program 

measures, no lethal or sublethal impacts would be anticipated (USDA APHIS, 2015). 

Indirect risk to reptiles from the loss of food items is expected to be low due to the low 

application rates and implementation of preferred program measures such as RAATs 

(USDA APHIS, 2018d).

The risk to aquatic vertebrates and invertebrates is low for most species; however, some 

sensitive species that occur in shallow water habitats may be at risk. Program measures 
30

such application buffer zones, drift mitigation measures and the use of RAATs will 

reduce these risks.

Risks to terrestrial invertebrate populations are anticipated based on the available toxicity 

data for invertebrates and the broad spectrum activity of malathion (Swain, 1986; Quinn 

et al., 1991). The risk to terrestrial invertebrates can be reduced by the implementation of 

application buffers and the use of RAATs, which would reduce exposure and create 

refuge areas where malathion impacts would be reduced or eliminated. Smith et al. 

(2006) conducted field studies to evaluate the impacts of grasshopper treatments to nontarget terrestrial invertebrates and found minimal impacts when making reduced rate 

applications with a reduced coverage area (i.e. RAATs) for a ULV end-use product of 

malathion. Impacts to pollinators have the potential to be significant, based on available 

toxicity data for honeybees that demonstrate high contact toxicity from malathion 

exposures (USDA APHIS, 2018d). However, risk to pollinators is reduced because of the 

short residual toxicity of malathion. In addition, the incorporation of other mitigation 

measures in the program, such as the use of RAATs and wind speed and direction 

mitigations that are designed to minimize exposure and reduce the potential for 

population-level impacts to terrestrial invertebrates.

Adverse human health effects from ULV applications of malathion to control 

grasshoppers are not expected based on the low mammalian acute toxicity of malathion 

and low potential for human exposure. Malathion inhibits AChE in the central and 

peripheral nervous system with clinical signs of neurotoxicity that include tremors, 

salivation, urogenital staining, and decreased motor activity. USEPA indicates that 

malathion has “suggestive evidence of carcinogenicity but not sufficient to assess human 

carcinogenic potential” (USEPA, 2016c). 

Adverse health risks to program workers and the general public from malathion exposure 

are also not expected due to low potential for exposure. APHIS treatments are conducted 

in rangeland areas consisting of widely scattered, single, rural dwellings in ranching 

communities, where agriculture is a primary industry. Label requirements to reduce 

exposure include minimizing spray drift, avoidance of water bodies and restricted entry 

interval. Program measures such as applying malathion once per season, lower 

application rates, application buffers and other measures further reduce the potential for 

exposure to the public.

b) Carbaryl

Carbaryl is a member of the N-methyl carbamate class of insecticides, which affect the 

nervous system via cholinesterase inhibition. Inhibiting the enzyme AChE causes 

nervous system signals to persist longer than normal. While these effects are desired in 

controlling insects, they can have undesirable impacts to non-target organisms that are 

exposed. The APHIS HHERA assessed available laboratory studies regarding the toxicity 

of carbaryl on fish and wildlife. In summary, the document indicates the chemical is 

highly toxic to insects, including native bees, honeybees, and aquatic insects; slightly to 

highly toxic to fish; highly to very highly toxic to most aquatic crustaceans, moderately 

toxic to mammals, minimally toxic to birds; moderately to highly toxic to several 
31

terrestrial arthropod predators; and slightly to highly toxic to larval amphibians (USDA 

APHIS, 2018a). 

The offsite movement and deposition of carbaryl after treatments is unlikely because it

does not significantly vaporize from the soil, water, or treated surfaces (Dobroski et al., 

1985). Temperature, pH, light, oxygen, and the presence of microorganisms and organic 

material are factors that contribute to how quickly carbaryl will degrade in water.

Hydrolysis, the breaking of a chemical bond with water, is the primary degradation 

pathway for carbaryl at pH 7 and above. In natural water, carbaryl is expected to degrade 

faster than in laboratory settings due to the presence of microorganisms. The half-lives of 

carbaryl in natural waters varied between 0.3 to 4.7 days (Stanley and Trial, 1980; 

Bonderenko et al., 2004). Degradation in the latter study was temperature dependent with 

shorter half-lives at higher temperatures. Aerobic aquatic metabolism of carbaryl reported 

half-life ranged of 4.9 to 8.3 days compared to anaerobic (without oxygen) aquatic 

metabolism range of 15.3 to 72 days (Thomson and Strachan, 1981; USEPA, 2003).

Carbaryl is not persistent in soil due to multiple degradation pathways including 

hydrolysis, photolysis, and microbial metabolism. Little transport of carbaryl through 

runoff or leaching to groundwater is expected due to the low water solubility, moderate 

sorption, and rapid degradation in soils. There are no reports of carbaryl detection in 

groundwater, and less than 1% of granule carbaryl applied to a sloping plot was detected 

in runoff (Caro et al., 1974).

Acute and chronic risks to mammals are expected to be low to moderate based on the 

available toxicity data and conservative assumptions that were used to evaluate risk. 

There is the potential for impacts to small mammal populations that rely on terrestrial 

invertebrates for food. However, based on the toxicity data for terrestrial plants, minimal 

risks of indirect effects are expected to mammals that rely on plant material for food. 

Carbaryl has a reported half-life on vegetation of three to ten days, suggesting mammal 

exposure would be short-term. Direct risks to mammals from carbaryl bait applications is 

expected to be minimal based on oral, dermal, and inhalation studies (USDA APHIS, 

2018a).

Numerous studies have reported no effects on bird populations in areas treated with 

carbaryl (Buckner et al., 1973; Richmond et al., 1979; McEwen et al., 1996). Some 

applications of formulated carbaryl were found to cause depressed AChE levels (Zinkl et 

al., 1977; Gramlich, 1979); however, the doses were twice those proposed for the full 

coverage application in the grasshopper program.

While sublethal effects have been noted in fish with depressed AChE, as well as some 

impacts to amphibians (i.e. days to metamorphosis) and aquatic invertebrates in the field 

due to carbaryl, the application rates and measured aquatic residues observed in these 

studies are well above values that would be expected from current program operations. 

Indirect risks to amphibian and fish species can occur through the loss of habitat or 

reduction in prey, yet data suggests that carbaryl risk to aquatic plants that may serve as 

habitat, or food, for fish and aquatic invertebrates is very low.
32

Product use restrictions appear on the USEPA-approved label and attempt to keep 

carbaryl out of waterways. Carbaryl must not be applied directly to water, or to areas 

where surface water is present (USEPA, 2012c). The USEPA-approved use rates and 

patterns and the additional mitigations imposed by the grasshopper program, such as 

using RAATs and application buffers, where applicable, further minimize aquatic 

exposure and risk.

Most rangeland plants require insect-mediated pollination. Native, solitary bee species 

are important pollinators on western rangeland (Tepedino, 1979). Potential negative 

effects of insecticides on pollinators are of concern because a decrease in their numbers 

has been associated with a decline in fruit and seed production of plants. Laboratory 

studies have indicated that bees are sensitive to carbaryl applications, but the studies were 

at rates above those proposed in the program. The reduced rates of carbaryl used in the 

program and the implementation of application buffers should significantly reduce 

exposure of carbaryl applications to pollinators. In areas of direct application where 

impacts may occur, alternating swaths and reduced rates (i.e., RAATs) would reduce risk. 

Potential negative effects of grasshopper program insecticides on bee populations may 

also be mitigated by the more common use of carbaryl baits than the ULV spray 

formulation. Studies with carbaryl bran bait have found no sublethal effects on adults or 

larvae bees (Peach et al., 1994, 1995).

Carbaryl can cause cholinesterase inhibition (i.e., overstimulate the nervous system) in 

humans resulting in nausea, headaches, dizziness, anxiety, and mental confusion, as well 

as convulsions, coma, and respiratory depression at high levels of exposure (NIH, 2009a;

Beauvais, 2014). USEPA classifies carbaryl as “likely to be carcinogenic to humans” 

based on vascular tumors in mice (USEPA, 2007, 2015a, 2017a).

USEPA regulates the amount of pesticide residues that can remain in or on food or feed 

commodities as the result of a pesticide application. The agency does this by setting a 

tolerance, which is the maximum residue level of a pesticide, usually measured in parts 

per million (ppm), that can legally be present in food or feed. USEPA-registered carbaryl 

products used by the grasshopper program are labeled with rates and treatment intervals 

that are meant to protect livestock and keep chemical residues in cattle at acceptable 

levels (thereby protecting human health). While livestock and horses may graze on 

rangeland the same day that the land is sprayed, in order to keep tolerances to acceptable 

levels, carbaryl spray applications on rangeland are limited to half a pound active 

ingredient per acre per year (USEPA, 2012c). The grasshopper program would treat at or 

below use rates that appear on the label, as well as follow all appropriate label 

mitigations, which would ensure residues are below the tolerance levels.

Adverse human health effects from the proposed program ULV applications of the 

carbaryl spray (Sevin® XLR Plus) and bait applications of the carbaryl 5% and 2% baits 

formulations to control grasshoppers are not expected based on low potential for human 

exposure to carbaryl and the favorable environmental fate and effects data. Technical 

grade (approximately 100% of the insecticide product is composed of the active 

ingredient) carbaryl exhibits moderate acute oral toxicity in rats, low acute dermal 

toxicity in rabbits, and very low acute inhalation toxicity in rats. Technical carbaryl is not 
33

a primary eye or skin irritant in rabbits and is not a dermal sensitization in guinea pig 

(USEPA, 2007). This data can be extrapolated and applied to humans revealing low 

health risks associated with carbaryl.

The Sevin® XLR Plus formulation, which contains a lower percent of the active 

ingredient than the technical grade formulation, is less toxic via the oral route, but is a 

mild irritant to eyes and skin. The proposed use of carbaryl as a ULV spray or a bait, use 

of RAATs, and adherence to label requirements, substantially reduces the potential for 

exposure to humans. Program workers are the most likely human population to be 

exposed. APHIS does not expect adverse health risks to workers based on low potential 

for exposure to carbaryl when applied according to label directions and use of personal 

protective equipment (PPE) (e.g., long-sleeved shirt and long pants, shoes plus socks, 

chemical-resistant gloves, and chemical-resistant apron) (USEPA, 2012c) during loading 

and applications. APHIS quantified the potential health risks associated with accidental 

worker exposure to carbaryl during mixing, loading, and applications. The quantitative 

risk evaluation results indicate no concerns for adverse health risk for program workers 

(http://www.aphis.usda.gov/plant-health/grasshopper).

Adherence to label requirements and additional program measures designed to reduce 

exposure to workers and the public (e.g., mitigations to protect water sources, mitigations 

to limit spray drift, and restricted-entry intervals) result in low health risk to all human 

population segments.

c) Diflubenzuron

Diflubenzuron is a restricted use pesticide (only certified applicators or persons under 

their direct supervision may make applications) registered with USEPA as an insect 

growth regulator. It specifically interferes with chitin synthesis, the formation of the 

insect’s exoskeleton. Larvae of affected insects are unable to molt properly. While this 

effect is desirable in controlling certain insects, it can have undesirable impacts to nontarget organisms that are exposed.

USEPA considers diflubenzuron relatively non-persistent and immobile under normal use 

conditions and stable to hydrolysis and photolysis. The chemical is considered unlikely to 

contaminate ground water or surface water (USEPA, 1997). The vapor pressure of 

diflubenzuron is relatively low, as is the Henry’s Law Constant value, suggesting the 

chemical will not volatilize readily into the atmosphere from soil, plants or water. 

Therefore, exposure from volatilization is expected to be minimal. Due to its low 

solubility (0.2 mg/L) and preferential binding to organic matter, diflubenzuron seldom 

persists more than a few days in water (Schaefer and Dupras, 1977; Schaefer et al., 

1980). Mobility and leachability of diflubenzuron in soils is low, and residues are usually 

not detectable after seven days (Eisler, 2000). Aerobic aquatic half-life data in water and 

sediment was reported as 26.0 days (USEPA, 1997). Diflubenzuron applied to foliage 

remains adsorbed to leaf surfaces for several weeks with little or no absorption or 

translocation from plant surfaces (Eisler, 1992, 2000). Diflubenzuron treatments are 

expected to have minimal effects on terrestrial plants. Both laboratory and field studies 

demonstrate no effects using diflubenzuron over a range of application rates, and the 

direct risk to terrestrial plants is expected to be minimal (USDA APHIS, 2018c).
34

Dimilin® 2L is labeled with rates and treatment intervals that are meant to protect 

livestock and keep residues in cattle at acceptable levels (thereby, protecting human 

health). Tolerances are set based on the amount of diflubenzuron that is allowed in cattle 

fat (0.05 ppm) and meat (0.05 ppm) (40 CFR Parts 180.377). The grasshopper program 

would treat at application rates indicated on product labels or lower, which should ensure 

approved residues levels. 

APHIS’ literature review found that on an acute basis, diflubenzuron is considered toxic 

to some aquatic invertebrates and practically non-toxic to adult honeybees. However, 

diflubenzuron is toxic to larval honeybees (USEPA, 2018). It is slightly nontoxic to 

practically nontoxic to fish and birds and has very slight acute oral toxicity to mammals, 

with the most sensitive endpoint from exposure being the occurrence of 

methemoglobinemia (a condition that impairs the ability of the blood to carry oxygen). 

Minimal direct risk to amphibians and reptiles is expected, although there is some 

uncertainty due to lack of information (USDA APHIS, 2018c; USEPA, 2018).

Risk is low for most non-target species based on laboratory toxicity data, USEPA 

approved use rates and patterns, and additional mitigations such as the use of lower rates 

and RAATs that further reduces risk. Risk is greatest for sensitive terrestrial and aquatic 

invertebrates that may be exposed to diflubenzuron residues.

In a review of mammalian field studies, Dimilin® applications at a rate of 60 to 280 g 

a.i./ha had no effects on the abundance and reproduction in voles, field mice, and shrews 

(USDA FS, 2004). These rates are approximately three to 16 times greater than the 

highest application rate proposed in the program. Potential indirect impacts from 

application of diflubenzuron on small mammals includes loss of habitat or food items. 

Mice on treated plots consumed fewer lepidopteran (order of insects that includes 

butterflies and moths) larvae compared to controls; however, the total amount of food 

consumed did not differ between treated and untreated plots. Body measurements, 

weight, and fat content in mice collected from treated and non-treated areas did not differ. 

Poisoning of insectivorous birds by diflubenzuron after spraying in orchards at labeled 

rates is unlikely due to low toxicity (Muzzarelli, 1986). The primary concern for bird 

species is related to an indirect effect on insectivorous species from a decrease in insect 

prey. At the proposed application rates, grasshoppers have the highest risk of being 

impacted while other taxa have a much reduced risk because the lack of effects seen in 

multiple field studies on other taxa of invertebrates at use rates much higher than those 

proposed for the program. Shifting diets in insectivorous birds in response to prey 

densities is not uncommon in undisturbed areas (Rosenberg et al., 1982; Cooper et al., 

1990; Sample et al., 1993).

Indirect risk to fish species can be defined as a loss of habitat or prey base that provides 

food and shelter for fish populations, however these impacts are not expected based on 

the available fish and invertebrate toxicity data (USDA APHIS, 2018c). A review of 

several aquatic field studies demonstrated that when effects were observed it was at 

diflubenzuron levels not expected from program activities (Fischer and Hall, 1992;

USEPA, 1997; Eisler, 2000; USDA FS, 2004). 
35

Diflubenzuron applications have the potential to affect chitin production in various other 

beneficial terrestrial invertebrates. Multiple field studies in a variety of application 

settings, including grasshopper control, have been conducted regarding the impacts of 

diflubenzuron to terrestrial invertebrates. Based on the available data, sensitivity of 

terrestrial invertebrates to diflubenzuron is highly variable depending on which group of 

insects and which life stages are being exposed. Immature grasshoppers, beetle larvae, 

lepidopteran larvae, and chewing herbivorous insects appear to be more susceptible to 

diflubenzuron than other invertebrates. Within this group, however, grasshoppers appear 

to be more sensitive to the proposed use rates for the program. Honeybees, parasitic 

wasps, predatory insects, and sucking insects show greater tolerance to diflubenzuron 

exposure (Murphy et al., 1994; Eisler, 2000; USDA FS, 2004). 

Diflubenzuron is moderately toxic to spiders and mites (USDA APHIS, 2018c). Deakle 

and Bradley (1982) measured the effects of four diflubenzuron applications on predators 

of Heliothis spp. at a rate of 0.06 lb a.i./ac and found no effects on several predator 

groups. This supported earlier studies by Keever et al. (1977) that demonstrated no 

effects on the arthropod predator community after multiple applications of diflubenzuron 

in cotton fields. Grasshopper integrated pest management (IPM) field studies have shown 

diflubenzuron to have a minimal impact on ants, spiders, predatory beetles, and 

scavenger beetles. There was no significant reduction in populations of these species 

from seven to 76 days after treatment. Although ant populations exhibited declines of up 

to 50 %, these reductions were temporary, and population recovery was described as 

immediate (Catangui et al., 1996).

Insecticide applications to rangelands have the potential to impact pollinators, and in turn, 

vegetation and various rangeland species that depend on pollinated vegetation. Based on 

the review of laboratory and field toxicity data for terrestrial invertebrates, applications of 

diflubenzuron are expected to have minimal risk to pollinators of terrestrial plants. The 

use of RAATs provide additional benefits by using reduced rates and creating untreated 

swaths within the spray block that will further reduce the potential risk to pollinators.

Adverse human health effects from ground or aerial ULV applications of diflubenzuron 

to control grasshoppers are not expected based on the low acute toxicity of diflubenzuron 

and low potential for human exposure. The adverse health effects of diflubenzuron to 

mammals and humans involves damage to hemoglobin in blood and the transport of 

oxygen. Diflubenzuron causes the formation of methemoglobin. Methemoglobin is a 

form of hemoglobin that is not able to transport oxygen (USDA FS, 2004). USEPA 

classifies diflubenzuron as non-carcinogenic to humans (USEPA, 2015b). 

Program workers adverse health risks are not likely when diflubenzuron is applied 

according to label directions that reduce or eliminate exposures. Adverse health risk to 

the general public in treatment areas is not expected due to the low potential for exposure 

resulting from low population density in the treatment areas, adherence to label 

requirements, program measures designed to reduce exposure to the public, and low 

toxicity to mammals.
36

d) Reduced Area Agent Treatments (RAATs) 

The use of RAATs is the most common application method for all program insecticides 

and would continue to be so except in rare pest conditions that warrant full coverage and 

higher rates. The goal of the RAATs strategy is to suppress grasshopper populations to a 

desired level, rather than to reduce those populations to the greatest possible extent. This 

strategy has both economic and environmental benefits. APHIS would apply a single 

application of insecticide per year, typically using a RAATs strategy that decreases the 

rate of insecticide applied by either using lower insecticide concentrations, and/or by 

alternating one or more treatment swaths. Usually RAATs applications use both options. 

The RAATs strategy suppresses grasshoppers within treated swaths, while conserving 

grasshopper predators and natural enemies (e.g. arachnids, blister beetles, robber flies, 

bee flies, and others) (see Manske, NDSU DREC for more) in swaths that are not treated. 

The concept of reducing the treatment area of insecticides while also applying less 

insecticide per treated acre was developed in 1995, with the first field tests of RAATs in 

Wyoming (Lockwood and Schell, 1997). Applications can be made either aerially or with 

ground-based equipment (Deneke and Keyser, 2011). Studies using the RAATs strategy 

have shown good control (up to 85% of that achieved with a traditional blanket 

insecticide application) at a significantly lower cost and less insecticide, and with a 

markedly higher abundance of non-target organisms following application (Lockwood et 

al., 2000; Deneke and Keyser, 2011). Levels of control may also depend on variables 

such as body size of targeted grasshoppers, growth rate of forage, and the amount of 

coverage obtained by the spray applications (Deneke and Keyser, 2011). Control rates 

may also be augmented by the necrophilic and necrophagic behavior of grasshoppers, in 

which grasshoppers are attracted to volatile fatty acids emanating from cadavers of dead 

grasshoppers and move into treated swaths to cannibalize cadavers (Lockwood et al., 

2002; Smith and Lockwood, 2003). Under optimal conditions, RAATs decrease control 

costs, as well as host plant losses and environmental effects (Lockwood et al., 2000; 

Lockwood et al., 2002). 

The efficacy of a RAATs strategy in reducing grasshoppers is less than conventional 

treatments and more variable. Foster et al. (2000) reported that grasshopper mortality 

using RAATs was reduced 2 to 15% from conventional treatments, depending on the 

insecticide, while Lockwood et al. (2000) reported 0 to 26% difference in mortality 

between conventional and RAATs methods. APHIS will consider the effects of not 

suppressing grasshoppers to the greatest extent possible as part of the treatment planning 

process. 

RAATs reduces treatment costs and conserves non-target biological resources in 

untreated areas. The potential economic advantages of RAATs was proposed by Larsen 

and Foster (1996), and empirically demonstrated by Lockwood and Schell (1997). 

Widespread efforts to communicate the advantages of RAATs across the western states 

were undertaken in 1998 and have continued on an annual basis. The viability of RAATs 

at an operational scale was initially demonstrated by Lockwood et al. (2000), and 

subsequently confirmed by Foster et al. (2000). The first government agencies to adopt 

RAATs in their grasshopper suppression programs were the Platte and Goshen County 

Weed and Pest Districts in Wyoming; they also funded research at the University of 
37

Wyoming to support the initial studies in 1995. This method is now commonly used by 

government agencies and private landowners in states where grasshopper control is 

necessary.

Reduced rates should prove beneficial for the environment. All APHIS grasshopper 

treatments using malathion, carbaryl, or diflubenzuron are conducted in adherence with 

USEPA-approved label directions. Labeled application rates for grasshopper control tend 

to be lower than rates used against other pests. In addition, use rates proposed for 

grasshopper control by APHIS are lower than rates used by private landowners.

3. Research Treatments Alternative

a) Research Metarhizium robertsii Applications 

Metarhizium is a common entomopathogenic fungus genus containing several species, all 

of which are host-restricted to the Arthropoda, with some having greater host specificity 

to an insect family, or even a group of related genera. Once considered a single species 

based on morphology but split into a number of species based on DNA sequence data, the 

genus is found worldwide and is commonly used as a management alternative to 

chemicals (USDA, 2000; Lomer et al., 2001; Zimmerman, 2007; Roberts, 2018; Zhang et 

al. 2019). Two Metarhizium, M. brunneum strain F52 and M. anisopliae ESF1, are 

registered with the USEPA as insecticides and are commercially used against a range of 

pest insects. 

No harm is expected to humans from exposure to Metarhizium by ingesting, inhaling, or 

touching products containing this active ingredient. No toxicity or adverse effects were 

seen when the active ingredient was tested in laboratory animals. M. anisopliae has 

undergone extensive toxicology testing for its registration in Africa and the registration of 

Green Guard in Australia. There has been no demonstrated adverse effect on humans 

from these products. There is a potential for an allergic reaction to dry conidia if a person 

is extensively exposed to the product and has a preexisting allergy to fungal spores. 

Metarhizium use in this program is not expected to cause adverse impacts to soil, water, 

or air. No adverse impacts from the use of Metarhizium biopesticides have been observed 

in almost 20 years of field trials in other countries.

From 2005 to 2017, a massive project (led by Donald W. Roberts, Utah State University, 

in collaboration with USDA and others, and funded by APHIS-PPQ-S&T) was 

undertaken to collect 38,052 soil samples from across the 17 western states, from areas 

that were historically known to have large populations of grasshoppers and/or Mormon 

crickets. The purpose of these collections was to locate a domestic alternative to the 

nonindigenous M. acridum, used around the world for management of grasshopper 

(usually locust) populations, particularly in Australia and sub-Sahelian Africa, but also in 

Mexico and Brazil. The use of such a pathogen would be highly useful to the Program as 

a biopesticide. Approximately 2,400 new isolates of Metarhizium spp., Beauveria spp.

and other entomopathogenic fungi were found. Many of these fungi isolates were 

selected for lab and field trials with grasshoppers and Mormon crickets, the most 

promising being strain DWR2009 belonging to the species M. robertsii (Bischoff et al., 
38

2009). The DWR2009 isolate is still undergoing lab and field testing for efficacy against 

orthopterans. This species is closely related to M. anisopliae, which is commonly found 

worldwide and discernible based on diagnostic DNA sequences (Roberts, 2018).

There is the potential for prolonged persistence in the environment of a domestic isolate 

from one area brought to another. Despite this possibility, potential environmental impact 

is minimal given the widespread and common nature of Metarhizium in the western 

United States and because the DWR2009 isolate have been chosen for their optimized 

effects on orthopterans (Roberts, 2018). Although entomopathogenic fungi can reduce 

grasshopper populations, a substantial portion of the treated population are able to resist 

the infection through thermoregulation. Molecular systematics analyses (by the Roberts 

Lab; Bischoff et al., 2009; Kepler et al., 2014; Mayerhofer et al., 2019) revealed 

DWR2009 is very closely related to many other strains within M. robertsii, all of which 

are basically biologically equivalent to each other. In fact, Metarhizium robertsii can only 

be differentiated from other species by a multiplexed PCR assay based on two gene 

sequences. Furthermore, it is likely that persistence effects would mirror those found for 

M. anisopliae and M. acridum. Both species need optimal temperature ranges to thrive, as 

well as relatively humid conditions (Zimmerman, 2007; EA, 2010). In particular, M. 

acridum does not persist in semi-arid and arid environments, which include rangeland 

habitats, where U.S. grasshopper outbreaks occur (EA, 2010). If the DWR2009 strain 

derived biopesticide is spread outside of the research plots, exceptional rates of fungal 

infection are not anticipated. Since M. anisopliae is a generalist entomopathogen, lethal 

effects on non-target arthropods have been reported, but are more commonly observed in 

laboratory experiments than in the field. Plus, such effects are dependent on how the 

pathogen is applied, (i.e., its intended target and application method play roles in nontarget effects) (Zimmerman, 2007). During experiments, the Rangeland Unit will spray 

ultra-low volumes (on 10 acres or less) of DWR2009 on grasshopper and Mormon 

cricket species from aircraft, or through the FAASSTT system. The Rangeland Unit may 

also coat small amounts of grasshopper bait with the DWR2009.

For the following four reasons, overall environmental impact by research studies utilizing 

Metarhizium robertsii applications should not be significant: 1) various strains of the 

pathogen are already common in rangeland habitats; 2) “behavioral fever” enables 

species to often “burn out” the infection by basking, allowing infected grasshoppers and 

Mormon crickets to escape death by mycosis; 3) fungal pathogens are fairly susceptible 

to heat and ultraviolet light, greatly reducing the environmental persistence of spores to a 

few days on treated foliage or ground; and 4) at least three days of 98-100% relative 

humidity is required for fungal outgrowth and sporulation (reproduction) from infected 

cadavers (Lomer et al., 2001; Zimmerman, 2007; EA, 2010; Roberts, 2018).

b) Research LinOilEx Applications 

LinOilEx (Formulation 103) is a non-traditional pesticide alternative still in the early 

stages of development. Its mode of action appears to be topical, often inducing a 

“freezing” effect in treated specimens whereby they appear to have been mid-movement 

when they die. Previous studies by its creator using locusts and katydids showed promise 
39

in its efficacy (Abdelatti and Hartbauer, 2019), so the Rangeland Unit decided to test it. 

Initial Mormon cricket microplot field studies and grasshopper lab studies are intriguing 

and warrant further field investigations via microplot cage experiments. The formulation 

is proprietary, but includes linseed oil, lecithin, wintergreen oil, and caraway oil mixed 

into a bicarbonate emulsion.

Target effects on locust and katydids in initial studies were high while non-target results 

were mixed, with one tested beetle species, as well as wheat seedlings, experiencing 

almost no impact. Another tested beetle species did experience relatively high mortality, 

but well-below target levels (Abdelatti and Hartbauer, 2019). The mode of action appears 

to be topical, meaning that direct contact with the formulation is needed to induce 

mortality. The Rangeland Unit’s initial studies demonstrated that indirect contact, by 

spraying vegetation, did not induce mortality. Together, these data suggest that overall 

environmental impact by research studies utilizing LinOilEx applications is expected to 

be relatively minimal.

B. Other Environmental Considerations

1. Cumulative Impacts

Cumulative impact, as defined in the Council on Environmental Quality (CEQ) NEPA 

implementing regulations (40 CFR § 1508.7) “is the impact on the environment which 

results from the incremental impact of the action when added to the past, present, and 

reasonably foreseeable future actions regardless of what agency (Federal or non-Federal) 

or person undertakes such actions. Cumulative impacts can result from individually 

minor but collectively significant actions taking place over a period of time.”

Potential cumulative impacts associated with the No Suppression alternative where 

APHIS would not organize or fund any grasshopper suppression programs include the 

continued increase in grasshopper populations and potential expansion of populations 

into neighboring range and cropland. In addition, State and private land managers could 

apply insecticides to manage grasshopper populations. However, land managers may opt 

not to use RAATs, which would increase insecticides applied to the environment. 

Increased insecticide use from the lack of coordination and RAAT applications, where 

suitable, could increase the exposure risk to non-target species and the environment. In 

addition, land managers may not employ the extra program measures designed to reduce 

exposure to the public and the environment. 

Potential cumulative impacts associated with the Preferred Alternative are expected to be 

minimal because the program applies an insecticide application once during a treatment. 

The program may treat an area with different insecticides, but does not overlap the 

treatments. The program does not mix or combine insecticides. Based on historical 

outbreaks in the United States, the probability of an outbreak occurring in the same area 

where treatment occurred in the previous year is unlikely; however, given time, 

populations eventually will reach economically damaging thresholds and require 

treatment. The insecticide application reduces the insect population down to levels that 

cause an acceptable level of economic damage. The duration of treatment activity, which 
40

is relatively short since it is a one-time application, and the lack of repeated treatments in 

the same area in the same year reduce the possibility of significant cumulative impacts.

Potential cumulative impacts resulting from the use of insecticides include insect pest 

resistance, synergistic chemical effects, chemical persistence and bioaccumulation in the 

environment. The program use of reduced insecticide application rates (i.e. ULV and 

RAATs) are expected to mitigate the development of insect resistance to the insecticides.

Grasshopper outbreaks in the United States occur cyclically so applications do not occur 

to the same population over time, further eliminating the selection pressure which 

increase the chances of insecticide resistance.

The insecticides proposed for use in the program have a variety of agricultural and nonagricultural uses. There may be an increased use of these insecticides in an area under 

suppression when private, State, or Federal entities make applications to control other 

pests. However, the vast majority of the land where program treatments occur is 

uncultivated rangeland and additional treatments by landowners or managers are very 

uncommon making possible cumulative or synergistic chemical effects extremely 

unlikely. 

The insecticides proposed for use in the grasshopper program are not anticipated to 

persist in the environment or bioaccumulate. Therefore, a grasshopper outbreak that 

occurs in an area previously treated for grasshoppers is unlikely to cause an accumulation 

of insecticides from previous program treatments.

The proposed research treatments are short-term and would take place in a very limited 

area. The purpose of the field tests conducted by the Rangeland Unit will help determine 

whether APHIS would eventually include Metarhizium robertsii (isolate DWR2009) 

based biopesticides as an option for the Program. The data generated by these studies 

would likely be used as part of the EPA registration process for this biopesticide. 

Inclusion of effective and environmentally friendly insecticides would provide the 

Program additional control options for grasshoppers and Mormon crickets in sensitive 

habitats. If successful, the use of M. robertsii could decrease the amount of chemical 

insecticides used in rangeland against grasshoppers and Mormon crickets.

2. Endangered Species Act

Under the Endangered Species Act of 1973, Section 7, federal agencies are required to 

consult with the USFWS regarding the degree of impact to federally proposed and listed 

species and critical habitat from the program action and the necessary protective 

measures to avoid or minimize adverse effects. Informal consultation between APHIS 

and the USFWS may be used to determine whether any adverse effects to species or 

habitat by the proposed action can be avoided or summarily minimized.

The last formal consultation resulted in the 1998 biological assessment prepared by 

APHIS and the 1995 biological opinion issued by USFWS. This environmental 

assessment uses information from past formal consultations in determining protective 

measures.
41

Malathion and carbaryl have been included in consultation procedures in the past. The 

1995 biological opinion has summarized the language from former assessments and 

opinions on the effects of both pesticides:

Carbaryl:

In general, carbaryl demonstrates low to moderate mammalian toxicity, low toxicity to 

birds, and moderate toxicity to fish. It is very toxic to aquatic invertebrates and many 

terrestrial insects. Carbaryl remains effective on vegetation for approximately seven days 

and 28 days in anaerobic soils (U.S. Fish and Wildlife Service, 1995).

Malathion:

Malathion is relatively low in toxicity to mammals and birds. It is moderately to highly 

toxic to fish and amphibians. Malathion is extremely toxic to aquatic invertebrates and 

highly toxic to most insects, including bees. Malathion is relatively non-persistent in soil, 

water, plants, and animals. Its half-life in alkaline soils is generally less than one day; in 

water, the half-life is generally less than two days. Malathion residues in plants persist 

up to five to seven days. Malathion does not bioaccumulate in animals; it is rapidly 

excreted after exposure ceases (U.S. Fish and Wildlife Service, 1995). 

Diflubenzuron: 

Further information on carbaryl, malathion, and diflubenzuron is included earlier in this 

EA, in the 2002 EIS and in the 2019 EIS. 

Due to the incomplete formal consultation, local informal consultations have been 

completed. Correspondence regarding local consultations between APHIS and USFWS 

are included in Appendix 2 “USFWS/NMFS/WGFD Correspondence”.

3. Monitoring 

Monitoring involves the evaluation of various aspects of the grasshopper suppression 

programs. There are three aspects of the programs that may be monitored. The first is 

the efficacy of the treatment. APHIS will determine how effective the application of an 

insecticide has been in suppressing the grasshopper population within a treatment area 

and will report the results in a Work Achievement Report to the Western Region. Work 

achievement reports are available from the Cheyenne, Wyoming USDA APHIS PPQ 

office for specific spray blocks upon request. No treatments were conducted in 2012, 

2013, 2014, 2015, 2016, 2017 or 2018 by PPQ in Wyoming.

The second area included in monitoring is safety. This includes ensuring the safety of the 

program personnel through medical monitoring conducted specifically to determine risks 

of a hazardous material. The cholinesterase health monitoring program is mandatory and 

prevents and/or reduces overexposure to cholinesterase inhibiting compounds such as 

carbamate and organophosphate pesticides. Since the effect of these pesticides is 

cumulative during a period of exposure, it is mandatory that all exposed individuals be 

monitored. The APHIS cholinesterase monitoring program will help protect employees 
42

from pesticide poisoning and will also help monitor the use and condition of personal 

protective equipment. APHIS program personnel are also provided proper hearing 

protection equipment. Chemical application equipment such as planes, trucks and 

sprayer motors may affect hearing if exposed for long periods of time. (See APHIS 

Safety and Health Manual, USDA APHIS, 1998 located online at 

https://www.aphis.usda.gov/aphis/resources/manualsandguidelines) 

The third area of monitoring is environmental monitoring. APHIS Directive 5640.1 

commits APHIS to a policy of monitoring the effects of Federal programs on the 

environment. Environmental monitoring includes such activities as checking to make 

sure the insecticides are applied in accordance with the labels, and that sensitive sites and 

organisms are protected. The environmental monitoring recommended for grasshopper 

suppression programs involves monitoring sensitive sites such as bodies of water used for 

human consumption or recreation or which have wildlife value, habitats of endangered 

and threatened species, habitats of other sensitive wildlife species, edible crops, and any 

sites for which the public has expressed concern or where humans might congregate (e.g. 

schools, parks, hospitals).

The current environmental monitoring plan can be found at 

https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-diseaseprograms/sa_emt/ct_support_docs. Past years environmental monitoring reports are 

available upon request from the Cheyenne, Wyoming USDA APHIS PPQ office.

Treatments conducted by PPQ in 2010 amounted to 1,027,099 protected acres. All 

treatments in 2010 were conducted using Dimilin 2L and RAATs methodology.

Treatments conducted by PPQ in 2011 amounted to 81,527 protected acres. All 

treatments in 2011 were conducted using Dimilin 2L and RAATs methodology.

No treatments were conducted by PPQ in Wyoming during 2012, 2013, 2014, 2015, 

2016, 2017 and 2018. 

Treatments conducted by PPQ in 2019 amounted to 130,902 protected acres. All 

treatments in 2019 were conducted using Dimilin 2L and RAATs methodology.

4. Fires and Human Health Hazards

Various compounds are released in smoke during wildland fires, including carbon 

monoxide (CO), carbon dioxide, nitrous oxides, sulfur dioxide, hydrogen chloride, 

aerosols, polynuclear aromatic hydrocarbons contained within fine particulate matter (a 

byproduct of the combustion of organic matter such as wood), aldehydes, and most 

notably formaldehyde produced from the incomplete combustion of burning biomass 

(Reisen and Brown, 2009; Burling et al., 2010; Broyles, 2013). Particulate matter, CO, 

benzene, acrolein, and formaldehyde have been identified as compounds of particular 

concern in wildland fire smoke (Reinhardt and Ottmar, 2004). 

Many of the naturally occurring products associated with combustion from wildfires may 

also be present as a result of combustion of program insecticides that are applied to 
43

rangeland. These combustion byproducts will be at lower quantities due to the short halflives of most of the program insecticides and their low use rates. Other minor combustion 

products specific to each insecticide may also be present as a result of combustion from a 

rangeland fire but these are typically less toxic based on available human health data 

(http://www.aphis.usda.gov/plant-health/grasshopper).

The safety data sheet for each insecticide identifies these combustion products for each 

insecticide as well as recommendations for PPE. The PPE is similar to what typically is 

used in fighting wildfires. Material applied in the field will be at a much lower 

concentration than what would occur in a fire involving a concentrated formulation.

Therefore, the PPE worn by rangeland firefighters would also be protective of any 

additional exposure resulting from the burning of residual insecticides. 

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47

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48

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Human Health and Ecological Risk Assessment for Carbaryl Rangeland 
49

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management. Annual Review of Entomology. 64:15-34.

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Bul. Environ. Contam. Toxicol. 17:379-386.
51

VI. Listing of Agencies and Persons Consulted 

Tyler A. Abbott

Field Supervisor

Wyoming State Office

Fish and Wildlife Service

United States Department of the Interior

5353 Yellowstone Rd. Suite 308a

Cheyenne, WY 82009

Kimberly Dickerson 

Environmental Contaminants Biologist

R6 WNS Coordinator

PUPs Database Administrator

Fish and Wildlife Service

United States Department of the Interior

334 Parsley Blvd

Cheyenne, WY 82007

Julie Proell Reeves

Plant and Wildlife Biologist

Wyoming Ecological Services Office

Fish and Wildlife Service

United States Department of the Interior

334 Parsley Blvd

Cheyenne, WY 82007

Ken Henke

Natural Resource Specialist

Bureau of Land Management

PO Box 1828

5353 Yellowstone Rd.

Cheyenne, WY 82009

Darren Long

Sage Grouse Biologist

Bureau of Land Management

PO Box 1828

5353 Yellowstone Rd.

Cheyenne, WY 82009

Chris Keefe

Wildlife Biologist

Wildlife and T & E Program Lead

Bureau of Land Management

PO Box 1828

5353 Yellowstone Rd.

Cheyenne, WY 82009

Noelle Gines-Bovio

WSA Coordinator

Bureau of Land Management

PO Box 1828

5353 Yellowstone Rd

Cheyenne, WY 82009

John Kennedy

Deputy Director

Wyoming Game and Fish

5400 Bishop Blvd

Cheyenne, WY 82006

Leslie Schreiber

Greater Sage-Grouse Coordinator

Wyoming Game and Fish

351 Astle Ave

Green River, WY 8935

Zach Walker

Non-Game Coordinator

Wyoming Game and Fish

260 Buena Vista

Lander, WY 82520

Ian Tator

Wildlife and Habitat Manager

Wyoming Game and Fish

5400 Bishop Blvd

Cheyenne, WY 82006
2

Appendix 1: APHIS Rangeland Grasshopper and Mormon Cricket 

Suppression Program FY-2020 Treatment Guidelines

Version 3/9/2020

The objectives of the APHIS Rangeland Grasshopper and Mormon Cricket Suppression Program 

are to 1) conduct surveys in the Western States; 2) provide technical assistance to land managers 

and private landowners; and 3) when funds permit, suppress economically damaging grasshopper 

and Mormon cricket outbreaks on Federal, Tribal, State, and/or private rangeland. The Plant 

Protection Act of 2000 provides APHIS the authority to take these actions. 

General Guidelines for Grasshopper / Mormon Cricket Treatments 

1. All treatments must be in accordance with: 

a. the Plant Protection Act of 2000; 

b. applicable environmental laws and policies such as: the National Environmental Policy 

Act, the Endangered Species Act, the Federal Insecticide, Fungicide, and Rodenticide 

Act, and the Clean Water Act (including National Pollutant Discharge Elimination 

System requirements – if applicable); 

c. applicable state laws; 

d. APHIS Directives pertaining to the proposed action; 

e. Memoranda of Understanding with other Federal agencies. 

2. Subject to the availability of funds, upon request of the administering agency, the agriculture 

department of an affected State, or private landowners, APHIS, to protect rangeland, shall 

immediately treat Federal, Tribal, State, or private lands that are infested with 

grasshoppers or Mormon crickets at levels of economic infestation, unless APHIS 

determines that delaying treatment will not cause greater economic damage to adjacent 

owners of rangeland. In carrying out this section, APHIS shall work in conjunction with 

other Federal, State, Tribal, and private prevention, control, or suppression efforts to 

protect rangeland. 

3. Prior to the treatment season, conduct meetings or provide guidance that allows for public 

participation in the decision making process. In addition, notify Federal, State and Tribal 

land managers and private landowners of the potential for grasshopper and Mormon 

cricket outbreaks on their lands. Request that the land manager / landowner advise 

APHIS of any sensitive sites that may exist in the proposed treatment areas. 

4. Consultation with local Tribal representatives will take place prior to treatment programs to 

fully inform the Tribes of possible actions APHIS may take on Tribal lands. 

5. On APHIS run suppression programs, the Federal government will bear the cost of treatment 

up to 100 % on Federal and Tribal Trust land, 50 % of the cost on State land, and 33 % of 

cost on private land. There is an additional 16.15 % charge, however, on any funds 

received by APHIS for federal involvement with suppression treatments. 
3

6. Land managers are responsible for the overall management of rangeland under their control to 

prevent or reduce the severity of grasshopper and Mormon cricket outbreaks. Land 

managers are encouraged to have implemented Integrated Pest Management Systems 

prior to requesting a treatment. In the absence of available funding or in the place of 

APHIS funding, the Federal land management agency, Tribal authority or other party/ies 

may opt to reimburse APHIS for suppression treatments. Interagency agreements or 

reimbursement agreements must be completed prior to the start of treatments which will 

be charged thereto.

7. There are situations where APHIS may be requested to treat rangeland that also includes small 

areas where crops are being grown (typically less than 10 % of the treatment area). In 

those situations, the crop owner pays the entire treatment costs on the croplands. 

NOTE: The insecticide being considered must be labeled for the included crop as well as 

rangeland and current Worker Protection Standards must be followed by the applicator 

and private landowner. 

8. In some cases, rangeland treatments may be conducted by other federal agencies (e.g., Forest 

Service, Bureau of Land Management, or Bureau of Indian Affairs) or by non-federal 

entities (e.g., Grazing Association or County Pest District). APHIS may choose to assist 

these groups in a variety of ways, such as: 

a. loaning equipment (an agreement may be required): 

b. contributing in-kind services such as surveys to determine insect species, 

instars, and infestation levels; 

c. monitoring for effectiveness of the treatment; 

d. providing technical guidance. 

9. In areas considered for treatment, State-registered beekeepers and organic producers shall be 

notified in advance of proposed treatments. If necessary, non-treated buffer zones can be 

established. 

Operational Procedures 

GENERAL PROCEDURES FOR ALL AERIAL AND GROUND APPLICATIONS 

1. Follow all applicable Federal, Tribal, State and local laws and regulations in conducting 

grasshopper and Mormon cricket suppression treatments. 

2. Notify residents within treatment areas, or their designated representatives, prior to proposed 

operations. Advise them of the control method to be used, proposed method of 

application, and precautions to be taken. 

3. One of the following insecticides that are labeled for rangeland use can be used for a 

suppression treatment of grasshoppers and Mormon crickets: 

A. Carbaryl 
4

a. solid bait 

b. ultra-low volume (ULV) spray 

B. Diflubenzuron ULV spray 

C. Malathion ULV spray

D. Chlorantraniliprole 

4. Do not apply insecticides directly to water bodies (defined herein as reservoirs, lakes, ponds, 

pools left by seasonal streams, springs, wetlands, and perennial streams and rivers). 

Furthermore, provide the following buffers for water bodies: 

· 500 foot buffer with aerial liquid insecticide. 

· 200 foot buffer with ground liquid insecticide. 

· 200 foot buffer with aerial bait. 

· 50 foot buffer with ground bait. 

5. Instruct program personnel in the safe use of equipment, materials and procedures; supervise 

to ensure safety procedures are properly followed. 

6. Conduct mixing, loading, and unloading in an approved area where an accidental spill would 

not contaminate a water body. 

7. Each aerial suppression program will have a Contracting Officer’s Representative (COR) OR 

a Treatment Manager on site. Each State will have at least one COR available to assist 

the Contracting Officer (CO) in GH/MC aerial suppression programs. 

NOTE: A Treatment Manager is an individual that the COR has delegated authority to oversee 

the actual suppression treatment; someone who is on the treatment site and overseeing / 

coordinating the treatment and communicating with the COR. No specific training is required, 

but knowledge of the Aerial Application Manual and treatment experience is critical; attendance 

to the Aerial Applicators Workshop is very beneficial. 

8. Each suppression program will conduct environmental monitoring as outlined in the current 

year’s Environmental Monitoring Plan. 

APHIS will assess and monitor rangeland treatments for the efficacy of the treatment, to 

verify that a suppression treatment program has properly been implemented, and to 

assure that any environmentally sensitive sites are protected. 

9. APHIS reporting requirements associated with grasshopper / Mormon cricket suppression 

treatments can be found in the APHIS Grasshopper Program Guidebook: 

http://www.aphis.usda.gov/import_export/plants/manuals/domestic/downloads/grasshopp

er.pdf. 
5

SPECIFIC PROCEDURES FOR AERIAL APPLICATIONS 

1. APHIS Aerial treatment contracts will adhere to the current year’s Statement of Work (SOW).

2. Minimize the potential for drift and volatilization by not using ULV sprays when the 

following conditions exist in the spray area: 

a. Wind velocity exceeds 10 miles per hour (unless state law requires lower wind speed); 

b. Rain is falling or is imminent; 

c. Dew is present over large areas within the treatment block; 

d. There is air turbulence that could affect the spray deposition; 

e. Temperature inversions (ground temperature higher than air temperature) develop and 

deposition onto the ground is affected. 

3. Weather conditions will be monitored and documented during application and treatment will 

be suspended when conditions could jeopardize the correct spray placement or pilot 

safety. 

4. Application aircraft will fly at a median altitude of 1 to 1.5 times the wingspan of the aircraft 

whenever possible or as specified by the COR or the Treatment Manager. 

5. Whenever possible, plan aerial ferrying and turnaround routes to avoid flights over congested 

areas, water bodies, and other sensitive areas that are not to be treated.
6

Appendix 2: USFWS/NMFS/WGFD Correspondence 
7
8
9
10
11
12

Appendix 3: Summary of Species Determinations and Impact 

Mitigation Measures 

1. Grizzly bear; Ursus arctos horribilis

a. Species Status Map

b. USFWS status: Threatened

APHIS grasshopper suppression programs will have no effect on the grizzly bear. 

It is not likely that APHIS grasshopper suppression programs will occur in areas of the 

bear’s preferred habitat, montane forests. If a suppression program does overlap with the 

habitat areas of the grizzly bear then a site specific consultation will be initiated with 

USFWS.
13

2. Northern Long-Eared Bat; Myotis septentrionalis

a. Species Status Map

b. USFWS Status: Threatened with a 4(d) rule

APHIS grasshopper suppression programs may affect but are not likely to 

adversely affect the Northern Long-Eared Bat. 

Wyoming is on the edge of the species range and there are no known active maternity areas in 

Wyoming. APHIS would use RAATs methodologies for treatments in most cases and this would 

be expected to leave adequate prey base for insectivorous species such as the NLEB. The 

preferred foraging areas for the NLEB are forested areas that would not receive grasshopper or 

Mormon cricket treatments. In addition, treatments would not occur during peak foraging 

activity reducing the potential for exposure to program insecticides. Dietary exposure from 

ingestion of contaminated prey or water is also not anticipated to be a major pathway of exposure 

for the northern long-eared bat. Indirect impacts to the NLEB from loss of invertebrate prey 

items due to program treatments are not anticipated. There may be insignificant or discountable 

effects to foraging resources or water due to grasshopper suppression programs outside of (but 

near to) the northern long-eared bat roosting and foraging areas. However grasshoppers and 

Mormon crickets are not the typical or primary prey for the northern long-eared bat.

Please see Appendix 5 for additional risk summary information.
14

3. Yellow billed Cuckoo; Coccyzus americanus

a. Species Status Map

b. USFWS Status: Threatened

APHIS grasshopper suppression programs may affect but are not likely to 

adversely affect the yellow billed cuckoo. The following mitigation measures will be 

followed:

1. Malathion and carbaryl ULV: 500 foot ground buffer and 1320 foot 

aerial buffer at the edge of known locations of yellow-billed cuckoos 

or their suitable habitat. 

2. Carbaryl bait: 500 foot ground buffer and 750 foot aerial buffer at the 

edge of known locations of yellow-billed cuckoos or their suitable

habitat. 

3. Diflubenzuron: 500 foot ground buffer and 1000 foot aerial buffer at 

the edge of known locations of yellow-billed cuckoos or their suitable

habitat. 

4. Chlorantraniliprole ULV: 500 foot ground/aerial buffer at the edge of 

known locations of yellow-billed cuckoos or their suitable habitat. 

Please see Appendix 4 for additional risk summary information.
15

4. Kendall Warm Springs dace; Rhinichthys osculus thermalis

a. Species Status Map

b. USFWS status: Endangered

Grasshopper suppression activities in Wyoming are not likely to adversely affect 

the Kendall warm springs dace. It is not likely that APHIS grasshopper suppression activities 

will occur in the vicinity of Kendall warm springs. If suppression activities are conducted in 

Sublette County then the following impact minimization efforts will be utilized. A 0.25 mile 

buffer shall be maintained around the Kendall warm springs site for all chemicals, and ground 

applications of malathion. For aerial applications of malathion, a 1 mile buffer will be 

maintained.
16

5. Black-footed ferret; Mustela nigripes

a. Species Status Map

b. USFWS status: Endangered

Grasshopper suppression activities in Wyoming are not likely to adversely affect 

black-footed ferrets. This determination is based on the fact that there are no known nonreintroduced black-footed ferret populations in Wyoming. 

 

c. USFWS Status: Experimental (Shirley Basin population)

There is one non-essential experimental population of black-footed ferrets in Wyoming. Located 

in the Shirley Basin, ferrets were reintroduced in 1991.

Grasshopper suppression activities in Wyoming are not likely to jeopardize the 

continued existence of the species based on the fact, by definition; any effects to an experimental 

non-essential population of any species will not jeopardize the continued existence of the 

species. The Shirley Basin recovery area has historically not been a high grasshopper density 

area so APHIS does not expect to have treatments in this area.
17

6. Canada Lynx; Lynx canadensis

a. Species Status Map

b. USFWS status: Threatened, Critical Habitat designated

APHIS grasshopper suppression programs will have no effect on the Canada 

Lynx or its designated critical habitat. It is not likely that APHIS grasshopper suppression 

programs will occur in areas of the lynx preferred habitat, boreal forests. If a suppression 

program does overlap with the critical habitat areas of the Canada Lynx then a site specific 

consultation will be initiated with USFWS.
18

7. Preble’s meadow jumping mouse; Zapus hudsonius preblei

a. Species Status Map

b. USFWS status: Threatened, Critical Habitat designated: Colorado only

Grasshopper suppression activities in Wyoming are not likely to adversely affect 

the Preble’s meadow jumping mouse. It is not likely that APHIS grasshopper suppression 

programs will occur in areas of the mouse’s preferred habitat, riparian areas due to a 

programmatic buffer placed on either side of streams or water bodies. This 500 foot buffer is 

standard procedure for all USDA APHIS PPQ grasshopper aerial suppression programs. For 

those areas that may be treated using ground equipment the 50 foot buffer will be increased to 

500 feet around waters and riparian areas that are Preble’s meadow jumping mouse suitable 

habitat, within the range of the species. 

In addition to the programmatic 200 foot ground treatment buffer and 500 foot 

aerial treatment buffer around bodies of water, to protect the Preble’s meadow jumping mouse 

and its prey base from ULV application of chlorantraniloprole, there will be a 500 foot treatment 

buffer from the edge of known occupied habitat or critical habitat.
19

8. Wyoming toad; Anaxyrus baxteri

a. Species Status Map

b. USFWS status: Endangered

Grasshopper suppression activities in Wyoming are not likely to adversely affect 

the Wyoming toad. It is not likely that APHIS grasshopper suppression activities will occur in 

the vicinity of Mortenson Lake. If suppression activities are conducted in Albany County then 

the following impact minimization efforts will be put into place. A one mile buffer for aerial 

spray shall be maintained on each side of the Little Laramie River and no treatments will be 

applied within a one mile buffer of Mortenson NWR.
20

9. Western Glacier Stonefly; Zapada glacier

a. Species Status Map

b. USFWS status: Threatened, Critical Habitat designated

Grasshopper suppression activities in Wyoming are not likely to adversely affect 

the Western Glacier Stonefly. It is not likely that APHIS grasshopper suppression programs will 

occur in areas of the stonefly’s habitat, riparian areas due to a programmatic buffer placed on 

either side of streams or water bodies. This 500 foot buffer is standard procedure for all USDA 

APHIS PPQ grasshopper aerial suppression programs. For those areas that may be treated using 

ground equipment the 50 foot buffer will be increased to 500 feet around waters and riparian 

areas that are Western Glacier Stonefly suitable habitat, within the range of the species. 

In addition to the programmatic 200 foot ground treatment buffer and 500 foot 

aerial treatment buffer around bodies of water, to protect the Western Glacier Stonefly from 

ULV application of chlorantraniloprole, there will be a 500 foot treatment buffer from the edge 

of known occupied habitat or critical habitat.
21

10. Ute ladies’ tresses; Spiranthes diluvialis

a. Species Status Map

b. USFWS status: Threatened

Grasshopper suppression activities in Wyoming are not likely to adversely affect 

the Ute ladies’ tresses. APHIS will take the following impact minimization measures for the 

protection of pollinators if a spray block occurs within known occupied habitat. The latest data 

available from WYNDD will be used to determine the known distribution of Ute ladies’ tresses. 

If treatments occur after August 1st the following buffers will be put in place for areas of 

potential habitat and known populations of Ute ladies’ tresses in addition to the programmatic 

500 foot buffer from water bodies.

1) No aerial application of malathion or carbaryl or gamma-cyhalothrin

within 3 miles of the known occupied habitat. 

2) Only carbaryl bran bait or diflubenzuron or chlorantraniliprole

combined with RAATs will be used within the 3 mile buffer.

3) No application of carbaryl bran bait will be applied within a 0.25 mile 

buffer of the potential range of species.

4) No buffer is required for diflubenzuron or chlorantraniliprole as they 

have no effect on adult insect pollinators. A 50 foot buffer for ground 

applications will be applied.
22

11. Blowout penstemon; Penstemon haydenii

a. Species Status Map

b. USFWS status: Endangered

Grasshopper suppression activities in Wyoming are not likely to adversely affect 

the blowout penstemon. APHIS will take the following impact minimization measures for the 

protection of pollinators if a spray block occurs within the USFWS potential range of species.

1) No aerial application of malathion or carbaryl or gamma-cyhalothrin

within 3 miles of the potential range of species. 

2) Only carbaryl bran bait or diflubenzuron or chlorantraniliprole

combined with RAATs will be used within the 3 mile buffer.

3) No application of carbaryl bran bait will be applied within a 0.25 mile 

buffer of the potential range of species.

4) No buffer is required for diflubenzuron or chlorantraniliprole as they 

have no effect on adult insect pollinators. A 50 foot buffer for ground 

applications will be applied. 
23

12. Desert Yellowhead; Yermo xanthocephalus

a. Species Status Map

b. USFWS status: Threatened, Critical Habitat designated

Grasshopper suppression activities in Wyoming are not likely to adversely affect 

the desert yellowhead or its designated critical habitat. APHIS will take the following impact 

minimization measures for the protection of pollinators if a spray block occurs within critical 

habitat or occupied habitat.

1. No aerial application of malathion or carbaryl or gamma-cyhalothrin

within 3 miles of the critical habitat or known occupied habitat. 

2. Only carbaryl bran bait or diflubenzuron or chlorantraniliprole

combined with RAATs will be used within the 3 mile buffer.

3. No application of carbaryl bran bait will be applied within a 0.25 mile 

buffer of the potential range of species.

4. No buffer is required for diflubenzuron or chlorantraniliprole as they 

have no effect on adult insect pollinators. A 50 foot buffer for ground 

applications will be applied.
24

13. River Species 

a. Platte River Species

Least Tern - Interior Population (Sterna antillarum) Status: Endangered

Pallid Sturgeon (Scaphirhynchus albus) Status: Endangered

Piping Plover (Charadrius melodus) Status: Endangered

Western Prairie Fringed Orchid (Platanthera praeclara) Status: Threatened

Whooping Crane (Grus americana) Status: Endangered
25

b. Colorado River Fish Species

Bonytail (Gila elegans) Status: Endangered

Coloradao Pikeminnow (Ptychocheilus lucius) Status: Endangered

Humpback Chub (Gila cypha) Status: Endangered

Razorback Sucker (Xyrauchen texamus) Status: Endangered

Grasshopper suppression activities in Wyoming will have no effect on any of the 

river species listed by the USFWS. Suppression activities will not deplete any water sources 

listed as tributaries to the Platte or Colorado River system nor will any activities have any effect 

on water quality downstream from Wyoming.
26

Appendix 4: Yellow-billed cuckoo (YBC) risk summary for 

grasshopper and Mormon cricket suppression program

The acute toxicity of Program insecticides, in particular carbaryl and diflubenzuron, range from 

practically non-toxic to highly toxic for birds, in the case of carbaryl, and practically non-toxic in 

the case of diflubenzuron (USDA APHIS, 2015). Carbaryl avian toxicity is variable based on 

the test species with the European starling, (Sturnis vulgaris) being the most sensitive and the 

ring-necked pheasant, Phasianus colchicus, being the least sensitive bird species (USDA APHIS, 

2015). Carbaryl acts by inhibiting the neurotransmitter, AChE, while diflubenzuron acts to 

inhibit chitin synthesis in developing invertebrates. Chronic toxicity between the two 

chemistries is similar with a lack of effects at field-relevant doses (USDA APHIS, 2015). The 

potential for risk to the YBC from the proposed use of program insecticides is related to the 

toxicity of each chemical and the probability of exposure which is discussed below.

Direct exposure to the YBC from proposed grasshopper and Mormon cricket applications is 

expected to be unlikely. The YBC use riparian habitats that contain willow-cottonwood and other 

woodland habitats. Optimal habitat size for the YBC is 200 acres with nesting rarely occurring 

in sites that are less than 50 acres. Forested areas typically have dense closed canopies. Nesting 

usually occurs in willow trees of various species but may also occur in other riparian tree species 

(USFWS, 2014). These are habitats that are not part of the Program for treatment and due to 

their proximity to water would have no application buffers regardless of whether they may 

contain YBC or their designated suitable habitat. In cases where there are YBC and/or suitable

habitat APHIS increases the no application buffer which further reduces the potential for direct 

exposure to any Program applications. Estimates of drift from the use of proposed treatments 

and no application buffers suggest that any potential residues that could move into YBC habitat 

would be below any potential for direct risk (USDA APHIS, 2015). The presence of dense, 

closed canopies of riparian trees in YBC habitat would also serve to intercept and remove the 

small amount of insecticide that could drift into these types of habitat. 

Dietary exposure from ingestion of contaminated prey or water is also not anticipated to be a 

major pathway of exposure for the YBC. There may be some incidental consumption of 

program insecticides that could be on the surface of some insect prey that receive a sublethal 

dose following treatment, however, there is not a plausible exposure scenario that could result in 

the ingestion of enough prey to result in risk to the YBC. Insects that receive a lethal dose would 

not be available for foraging by the YBC since they prefer live prey items. In the case of 

carbaryl bait applications, the probability of exposure would be less since the material is not 

applied as a liquid where it could result in residues on the surface of insects. Dietary exposure 

from the ingestion of contaminated surface water is also not anticipated to be a major pathway of 

exposure for the YBC. The program use of no application buffer zones from aquatic areas 

minimizes the potential for exposure to surface water. 

Indirect impacts to the YBC from loss of invertebrate and vertebrate prey items due to program 

treatments are not anticipated. The YBC has a varied diet including invertebrates as well as 

some vertebrates including tree frogs and lizards. Diet studies show that approximately 45% of 

its diet consists of lepidopteran larvae, followed by tree frogs (24%), katydids (22%), 
27

grasshoppers (9%) and the remaining amount from various invertebrates including, but not 

limited to beetles, flies, spiders, caddisflies, dragonflies, crickets and cicadas (USFWS, 2014). 

This preference may change based on availability of large invertebrate fauna. YBC prefer 

nesting and foraging in tree canopies along riparian corridors using a “sit and wait” strategy 

watching foliage movement for prey items (USFWS, 2014). The primary constituent elements 

and preferred habitat of YBC for nesting and foraging are not areas where the Program will be 

making applications. Proposed no application buffers from suitable habitat and known locations 

of the YBC, as well as the use of Reduced Agent Area Treatments (RAATs) where applications 

will occur adjacent to habitat would mitigate the impacts to potential food items for the YBC. In 

cases where YBC would forage outside of their preferred habitat there would be adequate food 

items for foraging based on their varied diet and the lack of effects to terrestrial invertebrates and 

vertebrates in the no application buffer zones that have been proposed, as well as negligible 

impacts to non-target terrestrial invertebrates and vertebrates in treatment blocks. The impacts to 

non-target invertebrates within treatment blocks from Program applications are summarized 

below and show minimal impacts to most non-target terrestrial invertebrates.

Available field studies suggest the program insecticide applications have minimal impacts to 

non-target terrestrial invertebrates (Quinn et al., 1990; Swain, 1986; Smith et al., 2006). Smith et 

al. (2006) assessed changes in non-target arthropod populations following applications of 

diflubenzuron, carbaryl, or malathion using RAATs. In the 2-year study, post application 

surveys of the major insect fauna revealed that only ants were negatively affected by grasshopper 

applications within treatment areas. As stated previously, Weiland et al. (2002) assessed the 

impacts of Sevin XLR Plus applications at 750 g a.i./ha to several invertebrate groups over a 21-

day period. This rate equates to 0.67 lb a.i./ac which is 1.34 times higher than the highest rate 

allowed in the program. Results from the study demonstrated no negative effects on abundance 

in the following insect groups: Homoptera, Hymenoptera, Coleoptera, Hemiptera, Lepidpotera, 

and Neuroptera. Previously conducted research, as well as field studies carried out as part of the 

grasshopper IPM project, indicates that diflubenzuron has minimal impact on most terrestrial 

non-target arthropods (Catangui et al., 1996). Weiland et al. (2002) in Wyoming monitored the 

effects of Dimilin 25W for 21 days post-application on terrestrial invertebrates after full 

treatment applications of 17.5 and 52.5 g a.i./ha. From high and low sweep net captures, no 

effect on invertebrates in the orders Homoptera, Hymenoptera, Coleoptera, Hemiptera, 

Lepidoptera, or Neuroptera were found. There was a statistically significant increase in Diptera 

and a statistically significant decrease in Araneae (spiders) but the authors question the spider 

analysis since untreated populations dropped dramatically during the study. Tingle (1996) 

assessed the impacts of diflubenzuron applications in two field trials occurring in two separate 

years with applications of 93 g a.i./ha (0.08 lb a.i./ac). Based on an analysis of 28 taxonomic 

groupings only two were affected and included non-target grasshoppers and lepidopteran larvae. 

This effect only occurred in the treated areas but did not occur in the untreated buffer areas that 

were sampled. Grasshopper IPM field studies have shown diflubenzuron to have a minimal 

impact on ants, spiders, predatory beetles, and scavenger beetles. There was no significant 

reduction in populations of these species from 7 to 76 days after treatment. Although ant 

populations exhibited declines of up to 50%, these reductions were temporary, and population 

recovery was described as immediate (Catangui et al., 1996). No significant reductions in flying 

non-target arthropods, including honey bees, were reported. Within one year of diflubenzuron 

applications in a rangeland environment, no significant reductions of bee predators, parasites, or 
28

pollinators were observed for any level of diflubenzuron treatment (Catangui et al., 1996). 

Graham et al. (2008) evaluated the impacts of diflubenzuron treatments on aquatic and terrestrial 

invertebrates for Mormon cricket suppression in Utah. Most terrestrial invertebrate taxa were 

not significantly different pre- and post-treatment among three sites that were evaluated. There 

was a noted decrease in some ant genera, but results were not consistent between sites and not all 

genera were impacted. Non-ant Hymenoptera showed increased numbers at two of the three 

sites and a decrease at a third site when comparing numbers pre- and post-treatment. Impacts to 

aquatic invertebrates, such as caddisflies and dragonflies, that may serve as prey for the YBC 

would be minimal due to the implementation of Program no-application buffer zones adjacent to 

aquatic habitat. Impacts to vertebrate food items for the YBC such as frogs and lizards would 

also be minimal based on risk estimates for each Program insecticide and the proposed 

mitigation to protect the YBC (USDA APHIS, 2015). 

Based on the qualitative risk assessment above and the proposed mitigation for protection of 

YBC and its suitable habitat, APHIS has determined that the Program may affect but is not likely 

to adversely affect the YBC.

References

Catangui, M.A., Fuller, B.W., and Walz, A.W., 1996. Impact of Dimilin on non-target

arthropods and its efficiency against rangeland grasshoppers. In Grasshopper Integrated Pest 

Management User Handbook, Tech. Bul. No.1809. Sec. VII.3. U.S. Department of Agriculture, 

Animal and Plant Health Inspection Service, Washington, DC.

Graham, T.B., Brasher, A.M.D., and Close, R.N., 2008, Mormon cricket control in Utah's west 

desert; evaluation of impacts of the pesticide diflubenzuron on non-target arthropod 

communities: U.S. Geological Survey Open-File Report 2008–1305, 82 p. 

[http://pubs.usgs.gov/of/2008/1305/].

Quinn, M.A., Kepner, R.L., Walgenbach, D.D., Foster, R.N., Bohls, R.A., Pooler, P.D., Reuter, 

K.C. and J.L. Swain. 1991. Effect of habitat and perturbation on populations and community 

structure of darkling beetles (Coleoptera: tenebrionidae) on mixed grass rangeland. Environ. 

Entomol. 19(6): 1746-1755.

Smith, D.I., Lockwood, J.A., Latchininsky, A.V., and Legg, D.E., 2006. Changes in non-target 

populations following applications of liquid bait formulations of insecticides for control of 

rangeland grasshoppers. Internat. J. Pest Mgt. 52(2):125-139.

Swain, J.L. 1986. Effect of chemical grasshopper controls on non-target arthropods of 

rangeland in Chaves County, New Mexico. Masters Thesis. New Mexico State University. 102 

pp.

Tingle, C.C.D. 1996. Sprayed barriers of diflubenzuron for control of the migratory locust 

(Locusta migratoria capito (Sauss.)) [Orthoptera: Acrididae] in Madagascar: short term impact 

on relative abundance of terrestrial non-target invertebrates. Crop Protection 15(6): 579-592.
29

USDA APHIS. 2015. Biological Assessment for the APHIS Rangeland Grasshopper and 

Mormon Cricket Suppression Program. Submitted to the USFWS March 2015.

U.S. Fish and Wildlife Service. 2014. Endangered and Threatened Wildlife and Plants; 

Designation of Critical Habitat for the Western Distinct Population Segment of the YellowBilled Cuckoo. Federal Register / Vol. 79, No. 158: 48548-48652.

Weiland, R.T., Judge, F.D., Pels, T., and Grosscurt, A.C., 2002. A literature review and new 

observations on the use of diflubenzuron for control of locusts and grasshoppers throughout the 

world. J. Orthoptera Res. 11(1):43-54.
30

Appendix 5: Northern long-eared bat (NLEB) risk summary for 

grasshopper and Mormon cricket suppression program

The acute toxicity of Program insecticides, in particular carbaryl and diflubenzuron, are 

considered moderate for mammals, in the case of carbaryl, and practically non-toxic in the case 

of diflubenzuron (USDA APHIS, 2015). Similar differences in toxicity between the two 

insecticides are seen in sublethal and chronic studies, as well. The difference in toxicity between 

the two insecticides is related to the mode of action. Carbaryl acts by inhibiting the 

neurotransmitter, AChE, while diflubenzuron acts to inhibit chitin synthesis in developing 

invertebrates. The potential for risk to the NLEB from the proposed use of program insecticides 

is related to the toxicity of each chemical and the probability of exposure. 

Direct exposure to the northern long-eared bat from proposed grasshopper and Mormon cricket 

applications is expected to be minimal. Program applications will occur during the day when 

bats are not foraging and would be under bark on trees, in crevices, and in mines or caves where 

exposure to drift would be limited (USFWS, 2014). Emerging at dusk, most hunting occurs 

above the understory, 1 to 3 meters (m) (3 to 10 feet (ft)) above the ground, but under the canopy 

(Nagorsen and Brigham, 1993) on forested hillsides and ridges, rather than along riparian areas 

(Brack and Whitaker, 2001; LaVal et al., 1977). This coincides with data indicating that mature 

forests are an important habitat type for foraging northern long-eared bats (Caceres and Pybus, 

1997). Occasional foraging also takes place over forest clearings and water, and along roads (van 

Zyll de Jong, 1985). Foraging patterns indicate a peak activity period within 5 hours after sunset 

followed by a secondary peak within 8 hours after sunset (Kunz, 1973). The preferred foraging 

areas for the NLEB are areas that would not receive grasshopper or Mormon cricket treatments. 

In addition, treatments would not occur during peak foraging activity reducing the potential for 

exposure to Program insecticides.

Dietary exposure from ingestion of contaminated prey or water is also not anticipated to be a 

major pathway of exposure for the northern long-eared bat. There may be some incidental 

consumption of program insecticides that could be on the surface of some insect prey that 

receive a sublethal dose following treatment, however, there is not a plausible exposure scenario 

that could result in the ingestion of enough prey based on the daily food consumption rates for 

similar Myotis species. Insects that receive a lethal dose would not be available for foraging by 

the NLEB since they prefer live prey items. In the case of carbaryl bait applications, the 

probability of exposure would be less since the material is not applied as a liquid where it could 

result in residues on the surface of insects. Dietary exposure from the ingestion of contaminated 

surface water is also not anticipated to be a major pathway of exposure for the NLEB. The 

program use of no application buffer zones from aquatic areas minimizes the potential for 

exposure to surface water. 

Indirect impacts to the NLEB from loss of invertebrate prey items due to program treatments are 

not anticipated. NLEB depends on a variety of invertebrates in its diet using foraging behaviors 

including hawking, and gleaning of insect prey from plant surfaces and water (Ratcliffe and 

Dawson, 2003). Its diet may include insects from the orders Lepidoptera, Neuroptera, 

Coleoptera, Trichoptera, Hymenoptera, Diptera, Hemiptera, and Homoptera (Thomas et al., 
31

2012; Feldhamer et al., 2009; Carter et al., 2003; Lee and McCracken, 2004). Coleoptera and 

Lepidoptera appear to make up the largest percentage of their diet, although proportions vary 

spatially and temporally, similar to other Myotis species, suggesting opportunistic feeding for 

available flying invertebrates (Griffith and Gates, 1985; Whitaker, 1972). Available field 

studies suggest the program insecticide applications have minimal impacts to non-target 

terrestrial invertebrates (Quinn et al., 1990; Swain, 1986; Smith et al., 2006). Smith et al. (2006)

assessed changes in non-target arthropod populations following applications of diflubenzuron, 

carbaryl, or Malathion using RAATs. In the 2-year study, post application surveys of the major 

insect fauna revealed that only ants were negatively affected by grasshopper applications within 

treatment areas. 

As stated previously, Weiland et al. (2002) assessed the impacts of Sevin XLR Plus applications 

at 750 g a.i./ha to several invertebrate groups over a 21-day period. This rate equates to 0.67 lb 

a.i./ac which is 1.34 times higher than the highest rate allowed in the program. Results from the 

study demonstrated no negative effects on abundance in the following insect groups: Homoptera, 

Hymenoptera, Coleoptera, Hemiptera, Lepidpotera, and Neuroptera. Previously conducted 

research, as well as field studies carried out as part of the grasshopper IPM project, indicates that 

diflubenzuron has minimal impact on most terrestrial non-target arthropods (Catangui et al., 

1996). Weiland et al. (2002) in Wyoming monitored the effects of Dimilin 25W for 21 days 

post-application on terrestrial invertebrates after full treatment applications of 17.5 and 52.5 g 

a.i./ha. From high and low sweep net captures, no effect on invertebrates in the orders 

Homoptera, Hymenoptera, Coleoptera, Hemiptera, Lepidpotera, or Neuroptera were found. 

There was a statistically significant increase in Diptera and a statistically significant decrease in 

Araneae (spiders) but the authors question the spider analysis since untreated populations 

dropped dramatically during the study. Tingle (1996) assessed the impacts of diflubenzuron 

applications in two field trials occurring in two separate years with applications of 93 g a.i./ha 

(0.08 lb a.i./ac). Based on an analysis of 28 taxonomic groupings only two were affected and 

included non-target grasshoppers and lepidopteran larvae. This effect only occurred in the 

treated areas but did not occur in the untreated buffer areas that were sampled. Grasshopper IPM 

field studies have shown diflubenzuron to have a minimal impact on ants, spiders, predatory 

beetles, and scavenger beetles. There was no significant reduction in populations of these 

species from 7 to 76 days after treatment. Although ant populations exhibited declines of up to 

50 %, these reductions were temporary, and population recovery was described as immediate 

(Catangui et al., 1996). No significant reductions in flying non-target arthropods, including 

honey bees, were reported. Within 1 year of diflubenzuron applications in a rangeland 

environment, no significant reductions of bee predators, parasites, or pollinators were observed 

for any level of diflubenzuron treatment (Catangui et al., 1996). Graham et al. (2008) evaluated 

the impacts of diflubenzuron treatments on aquatic and terrestrial invertebrates for Mormon 

cricket suppression in Utah. 

Most terrestrial invertebrate taxa were not significantly different pre- and post-treatment among 

three sites that were evaluated. There was a noted decrease in some ant genera, but results were 

not consistent between sites and not all genera were impacted. Non-ant Hymenoptera showed 

increased numbers at two of the three sites and a decrease at a third site when comparing 

numbers pre- and post-treatment. Impacts to aquatic invertebrates that may serve as prey would 
32

be minimal due to the implementation of Program no-application buffer zones adjacent to 

aquatic habitat. 

Based on the qualitative risk assessment above, APHIS has determined that the Program will not 

jeopardize the continued existence of the northern long-eared bat foraging and in roosts in the 

program area. 

References

Brack, V. and J.O. Whitaker. 2001. Foods of the northern myotis, Myotis septentrionalis, from 

Missouri and Indiana, with notes on foraging. Acta chiropterologica. 3: 203–210. 

Caceres, M.C., and M. J. Pybus. 1997. Status of the northern long-eared bat (Myotis 

septentrionalis) in Alberta. Alberta Environmental Protection, Wildlife Management Division, 

Wildlife Status Report No. 3, Edmonton, AB. 

Carter, T.C., M.A. Menzel, S.F. Owen, J.W. Edwards, J.M. Menzel, and W.M. Ford. 2003. 

Food habits of seven species of bats in the Allegheny plateau and ridge valley of West Virginia. 

Northeastern Nat. 10(1):83.88.

Catangui, M.A., Fuller, B.W., and Walz, A.W., 1996. Impact of Dimilin on non-target

arthropods and its efficiency against rangeland grasshoppers. In Grasshopper Integrated Pest 

Management User Handbook, Tech. Bul. No.1809. Sec. VII.3. U.S. Department of Agriculture, 

Animal and Plant Health Inspection Service, Washington, DC.

Feldhamer, G.A., T.C. Carter, J.O. Whitaker, Jr. 2009. Prey Consumed by Eight Species of 

Insectivorous Bats from Southern Illinois. The American Midland Naturalist. 162(1): 43–51.

Graham, T.B., Brasher, A.M.D., and Close, R.N., 2008, Mormon cricket control in Utah's west 

desert; evaluation of impacts of the pesticide diflubenzuron on non-target arthropod 

communities: U.S. Geological Survey Open-File Report 2008–1305, 82 p. 

[http://pubs.usgs.gov/of/2008/1305/].

Griffith, L.A. and J.E. Gates. 1985. Food habits of cave-dwelling bats in the central 

Appalachians. Journal of Mammalogy. 66(3): 451−460.

Kunz, T.H. 1973. Temporal and Spatial Components of Bat Activity in Central Iowa. Journal of 

Mammalogy. 54(1): 14–32.

LaVal, R. K., R. L. Clawson, M. L. LaVal and W. Caire. 1977. Foraging Behavior and Nocturnal 

Activity Patterns of Missouri Bats, with Emphasis on the endangered species Myotis grisescens 

and Myotis sodalis. Journal of Mammalogy. 58(4): 592−599.

Lee, Y.F. and G.F. McCracken. 2004. Flight activity and food habits of three species of Myotis 

bats (Chiroptera: Vespertilionidae) in sympatry. Zoological Studies 43(3): 589-597.

Nagorsen, D.W., and R.M. Brigham. 1993. The Mammals of British Columbia. 1. Bats. 
33

Royal British Columbia Museum, Victoria, and the University of British Columbia Press, 

Vancouver. pp. 16412.

Quinn, M.A., Kepner, R.L., Walgenbach, D.D., Foster, R.N., Bohls, R.A., Pooler, P.D., Reuter, 

K.C. and J.L. Swain. 1991. Effect of habitat and perturbation on populations and community 

structure of darkling beetles (Coleoptera: tenebrionidae) on mixed grass rangeland. Environ. 

Entomol. 19(6): 1746-1755.

Ratcliffe, J.M., and J.W. Dawson. 2003. Behavioral flexibility: the little brown bat, Myotis 

lucifugus, and the northern long-eared bat, M. septentrionalis, both glean and hawk prey. Animal 

Behaviour 66: 847−856.

Smith, D.I., Lockwood, J.A., Latchininsky, A.V., and Legg, D.E., 2006. Changes in non-target 

populations following applications of liquid bait formulations of insecticides for control of 

rangeland grasshoppers. Internat. J. Pest Mgt. 52(2):125-139.

Swain, J.L. 1986. Effect of chemical grasshopper controls on non-target arthropods of 

rangeland in Chaves County, New Mexico. Masters Thesis. New Mexico State University. 102 

pp.

Thomas, H. H., P.R. Moosman, Jr., J.P. Veilleux, and J. Holt. 2012. Foods of bats (Family 

Vespertilionidae) at five locations in New Hampshire and Massachusetts. Canadian FieldNaturalist 126(2): 117–124.

Tingle, C.C.D. 1996. Sprayed barriers of diflubenzuron for control of the migratory locust 

(Locusta migratoria capito (Sauss.)) [Orthoptera: Acrididae] in Madagascar: short term impact 

on relative abundance of terrestrial non-target invertebrates. Crop Protection 15(6): 579-592.

USDA APHIS. 22015. Biological Assessment for the APHIS Rangeland Grasshopper and 

Mormon Cricket Suppression Program 

U.S. Fish and Wildlife Service. 2014. Northern long-eared bat interim conference and planning 

guidance. 67 pp.

Weiland, R.T., Judge, F.D., Pels, T., and Grosscurt, A.C., 2002. A literature review and new 

observations on the use of diflubenzuron for control of locusts and grasshoppers throughout the 

world. J. Orthoptera Res. 11(1):43-54.

Whitaker, J.O., Jr. 1972. Food habits of bats from Indiana. Canadian Journal of Zoology. 50(6): 

877−883.
34

Appendix 6: Comments received during the open comment period

USDA APHIS received several public responses to the publication of the Wyoming draft EA 

(EA Number: WY-20-01). Public comments were received from BLM field offices, WGFD and 

USFWS. Public comments were also received from the Xerces Society and from the Center for 

Biological Diversity. Comments similar in nature were grouped under one response. Comments 

that were editorial in nature or requested additional citations are not addressed in the appendix 

but were incorporated into the final EA, where appropriate. The Grasshopper Program has 

decided not to use chlorantraniliprole in Wyoming during 2020, any exposure scenarios which 

the commenters are concerned about are not relevant, and references to this chemical has been 

removed from the final EA.

Comment 1 

USDA APHIS received one comment about the EA providing little in the way of solid 

information about where, how, and when the treatments may actually occur within the counties 

covered under the EAs, during the year 2020, which makes it impossible to determine if effects 

would actually be significant or not. 

APHIS described the purpose and need for grasshopper suppression treatments, potential 

treatment options, the affected environment within the state, and an analysis of the potential 

environmental consequences in the Draft EA that were made available for public comment. 

These documents become programmatic because APHIS cannot precisely predict where an 

outbreak will occur each year; we only know that outbreaks will occur, and treatments in a 

timely manner will be absolutely necessary. The emergency response aspect is why site-specific 

treatment details cannot be known, analyzed, and published in advance. APHIS relies on its 

emergency provisions within its NEPA Implementing Regulations (7 CFR 372.10) to address 

these situations.

Please be aware that as per conversations with BIA may preclude disclosure of Tribal 

information to the public or outside of APHIS without the consent of BIA or the Tribes. 

Individuals may request information on the specific treatment areas on Tribal Lands from the 

individual Tribal Nations or the Bureau of Indian Affairs.

Comment 2 

USDA APHIS received one comment concerning the lack of transparency about the location of 

actual treatment areas, particularly on public lands, being a disservice to the public that prevents 

the public from reviewing sufficient information to be able to gauge justification for and the risks 

involved in the suppression effort. 

APHIS did not withhold the location of actual treatment areas while preparing the Draft EA, but 

rather those facts were not known at that time because economically damaging grasshopper 

populations had not become apparent. See previous comment concerning the prevention of the 

commenter’s ability to gauge the justification and risks of treatments within the proposed action 

areas. 
35

Comment 3

APHIS received one comment urging APHIS to provide the public with maps of specific 

treatment areas and proposed treatment strategies (including proposed date of application and 

chemical and rate to be used), immediately after approving any treatment and at least 14 days 

prior to implementation of any treatment. This comment suggested that this specific information 

be posted at the APHIS website as soon as it is available, sent to interested parties, and made 

available for public comment.

In most circumstances, APHIS is not able to accurately predict specific treatment areas 

and treatment strategies months or even weeks before grasshopper populations reach economic 

infestation levels. The need for rapid and effective response when an outbreak occurs limits the 

options available to APHIS to inform the public other than those stakeholders who could be 

directly affected by the actual application. APHIS typically does not have 14 days between 

planning a treatment and the actual application because of the rapid population growth 

and potential damage of grasshopper infestations. 

Please be aware that as per conversations with BIA may preclude disclosure of Tribal 

information to the public or outside of APHIS without the consent of BIA or the Tribes. 

Individuals may request information on the specific treatment areas on Tribal Lands from the 

individual Tribal Nations or the Bureau of Indian Affairs.

Comment 4

APHIS received one comment that mentioned “APHIS’ procedure to approve or disapprove 

treatments based on a cost-benefit analysis performed using the “Hopper” model” and that is 

site-specific data are not available or current, APHIS must use protective values as defaults in 

Hopper.”

 

The “Hopper” model is an older model and is no longer used in Wyoming.

In Wyoming, general site specific data, which is used to determine treatments in real time and 

gathered at time of actual surveys are used to make treatment decisions. The general site specific 

data include: grasshopper densities, species complex, dominant species, dominant life stage, 

range conditions, local weather patterns (wind, temp., and precipitation), and known historical

hatching beds. Land owners and land managers consider other factors such as animal unit 

months (AUM’s) present in grazing allotment, forage damage estimates, number of potential 

AUM’s consumed by grasshopper population, potential AUM’s managed for allotment and value 

of the AUM, estimated cost of replacement feed for livestock, rotational time frame for grazing 

allotments, and the number of livestock in grazing allotment when requesting APHIS’s 

assistance. These are all factors taken into consideration during this cooperative decision 

making process during the survey season. 

Comment 5

APHIS received one comment concerning how analysis of projected economic injury levels and 

ultimately, treatment decisions, might be determined in the absence of site-specific data 

(specifically rangeland productivity and composition, precipitation and soil moisture, 
36

accessibility and cost of alternative forage, effectiveness of treatment, cost of treatment, timing 

of treatment, and grasshopper population density, life stage, and species composition).

See comment 4 above. In Wyoming, general site specific data, which is used to determine 

treatments in real time and gathered at time of actual surveys are used to make treatment 

decisions. This decision making process is a cooperative effort between the requesting land 

owners and land managers and APHIS.

Comment 6

APHIS received one comment related to disclosing its analysis for each of the seven variables 

mentioned in comment 5.

The site specific data that is used to determine treatments in real-time is gathered at the time of 

actual surveys. This data is not available at the time that the environmental assessments are 

prepared. See comment 4 for an example of general site specific data used to determine 

treatments.

Please be aware that as per conversations with BIA may preclude disclosure of Tribal 

information to the public or outside of APHIS without the consent of BIA or the Tribes. 

Individuals may request information on the specific treatment areas on Tribal Lands from the 

individual Tribal Nations or the Bureau of Indian Affairs.

Comment 7

APHIS received one comment about providing the public with a more precise definition of when 

the threshold for spraying has been met.

Economic thresholds are variable based on the value of protected resources and management 

objectives. Baseline thresholds for Mormon crickets are 2 per sq. yd. and grasshoppers are 

8 per sq. yd., though neither of those thresholds guarantees justification for treatment alone. All 

of the site-specific data mentioned in comment 4 above are also considered for Wyoming.

Comment 8

APHIS received one comment urging APHIS to delay the publication of EA and FONSI until 

after treatment requests are received and all treatment areas have been delineated and are 

identified to the public.

In Wyoming, it is necessary to complete the EA and FONSI prior to the start of field season.

Delaying the publication of the EA and FONSI would make responding to requests from land 

owners and land managers unreasonable. Cooperating agency’s which tier their NEPA 

documents to APHIS’s need a reasonable amount of time before or at the start of the field season 

and specific treatment decisions are made during the nymphal survey which, due to grasshopper 

biology, need to be timely in order to use APHIS’ preferred chemical and most ecologically 

sound treatment strategies. 
37

Comment 9

APHIS received one comment regarding the EA’s list three insecticide options (diflubenzuron, 

carbaryl, and malathion), and states that the choice of which to use will be site-specific, without 

being clear about how that choice of insecticide is made.

Letters of Request in previous years from land managers may be specific to use a particular 

insecticide and not treat during specific times of the day or on weekends and may include special 

sites to be buffered out of the treatment. These requests are adhered to in Wyoming. The letters 

of request come from the individual land managers. The decision to use diflubenzuron is 

determined by the life stage of the dominant species within the outbreak population. In the case 

of early instars, diflubenzuron, the preferred insecticide, can produce 90 to 97% mortality. If the 

window for the use of diflubenzuron closes, as a result of treatment delays, then the only other 

option would be the use of Carbaryl 2% or 5% bait. There are certain species which are 

susceptible to carbaryl bait. If the species complex present in the outbreak is not susceptible to 

bait and the diflubenzuron window is closed, then no treatments will occur. This is 

discussed with the requesting land managers. 

The final EA has been updated to reflect the changes in the program.

Comment 10

APHIS received one comment concerning BeeREX calculating the expected environmental 

concentration (EEC) of diflubenzuron in pollen and nectar from foliar overspray as 1.76 mg/kg, 

which is equivalent to 1760 ppb.

Nectar and pollen values in BeeREX are based on residues that would be expected to occur from 

direct pesticide applications to long grass which is a food source EPA estimates in its T-REX 

model. These assumptions may overestimate expected residues of diflubenzuron in pollen and 

nectar. Available data for diflubenzuron pollen residues in crops show a low frequency of 

occurrence and low concentrations. The concentration in pollen will depend on application 

rates and when applications are made relative to flower bloom. Program applications of 

diflubenzuron are at the lower end of labeled use rates for Dimilin due to the sensitivity of 

Orthoptera. In addition, the Program uses rates less than the current labeled rates for 

grasshoppers and other labeled crops and makes only one application.

Comment 11

APHIS received one comment regarding chitin synthesis and it’s importance in the early life 

stages of insects, as they molt and form a new exoskeleton in various growth stages. The specific 

concern was that aquatic guideline tests, (or terrestrial invertebrate acute tests), which typically 

run for 48 hours, may not capture a molting stage, and thus underrepresent acute toxicity. Single 

doses may cause mortality, if received at a vulnerable time, and consequently, conclusions from 

RQs based on acute toxicity studies for invertebrates may not fully represent actual risk.

APHIS agrees that chitin synthesis is a critical function for terrestrial and aquatic invertebrates.

APHIS in its risk assessments prepared for each Program insecticide summarized available 

acute and chronic toxicity data. This would include studies of short duration such as 48 to 96 
38

hours as well as much longer term studies that would evaluate continuous exposures during 

critical life stages and development.

Comment 12

APHIS received the following comment, “For honey bees (the surrogate species for risk

assessment in the absence of other data), USEPA (2018) reported a chronic 21-day ED50 and 

NOAEL of 0.012 and <0.0064 μg a.i./larva, respectively. Utilizing these values 

in BeeREX (EPA’s model that calculates risk quotients for bees) and assuming an application 

rate of 0.016 lb. a.i./ac, BeeREX calculates an acute dietary risk quotient of 18.13 and a chronic 

dietary risk quotient of 33.99. (A threshold value is 1.0). Risk quotients this high above 1.0 

indicate a high concern for exposed bees.”

BeeREX is a tier one screening level model used by EPA to assess potential risk to pollinators. 

Estimates of risk quotients are used to determine if there is a presumption of risk that requires 

additional evaluation. APHIS also relies on available field data to further characterize the risks 

of Program insecticides to terrestrial and aquatic invertebrates, where available. A limitation 

of BeeREX is it does not account for pesticide degradation that would normally occur in 

Program treatments.

Nectar and pollen values in BeeREX are based on residues that would be expected to occur from 

direct pesticide applications to long grass which is a food source EPA estimates in its T-REX 

model. These assumptions may overestimate expected residues of diflubenzuron in pollen and 

nectar. Available data for diflubenzuron pollen residues in crops with higher use rates show a 

low frequency of occurrence and low concentrations. The concentration in pollen will depend 

on application rates and when applications are made relative to flower blooming. Diflubenzuron 

Program applications are at the lower end of labeled use rates for Dimilin due to the sensitivity 

of Orthoptera. In addition, the Program uses rates less than the current labeled rates and makes 

one application.

Comment 13

APHIS received one comment, regarding the EIS disclosing that under some 

circumstances, Dimilin may be quite persistent; field dissipation studies in California citrus and 

Oregon apple orchards reported half-live values of 68.2 to 78 days. Rangeland persistence is 

unfortunately not available, but diflubenzuron applied to plants remains adsorbed to leaf surfaces

for several weeks.

Diflubenzuron persistence varies depending on site conditions. Diflubenzuron degradation is 

microbially mediated with soil aerobic half-lives much less than dissipation half-lives. While 

dissipation half-lives may extend up to 78 days, they have also been shown to be much less under 

other use patterns.

Comment 14

APHIS received the following comment, “APHIS discounted the pollinator risk by claiming that 

studies finding significant effects to pollinators utilized doses far above levels that would be used 

in grasshopper control. Unfortunately, this does not appear to be true for all studies 

cited. Mommaerts et al. (2006) conducted dose-response assays and found that exposure to 
39

diflubenzuron resulted in reproductive effects in Bombus terrestris, with only the doses at 0.001 

of maximum field recommended concentrations (MFRC) in pollen and 0.0001 in sugar water 

resulting in effects statistically similar to controls. The MFRC for diflubenzuron is listed in the 

study as 288 mg/L (equivalent to 288,000 ppb). At 1/10,000 of this level, diflubenzuron effects 

would be similar to controls only at levels at or below 28.8 ppb while at 1/1000 of this level, 

diflubenzuron “no effect” concentrations would be equivalent to 288 ppb. This analysis thus 

shows the opposite of what APHIS claims – that the effective dose for reproductive effects is 

actually far below the EEC expected for diflubenzuron at RAATS rates used in grasshopper 

suppression. This raises concern that the application of diflubenzuron at the specified RAATS 

rates may cause severe impacts to bee reproduction within treated areas.”

APHIS relied on available laboratory and field collected data for each Program insecticide to 

summarize risks to terrestrial invertebrates. In evaluating studies, APHIS also evaluated likely 

routes of exposure for Program treatments. Estimates of exposure using the EPA tier one 

screening model likely overestimate potential residues in pollen and nectar. 

Comment 15

APHIS received six comments about chlorantraniliprole.

Chlorantraniliprole is not proposed for use in Wyoming in 2020. Appendix 1: APHIS Rangeland 

Grasshopper and Mormon Cricket Suppression Program FY-2020 Treatment Guidelines are 

updated for the national grasshopper program for all 17 western states. The final EA has been 

updated to reflect the changes in the program.

Comment 16

APHIS received one comment concerning malathion being found to cause jeopardy in 1,284 

endangered species according to recent nationwide Biological Opinions

APHIS recognizes that EPA and the Services are continuing to develop updated national level 

consultations. APHIS currently consults with the Services at the State level for the Grasshopper 

program to ensure program activities do not adversely affect protected species or their critical 

habitat. 

See response to comment 9 for use of Malathion in Wyoming.

Comment 17

APHIS received one comment regarding the EPA determined that carbaryl is likely to adversely 

affect 1,542 species.

The Endangered Species Act section 7 pesticide consultation process between the U.S. Fish and 

Wildlife Service and the National Marine Fisheries Service (the Services, collectively) and the 

EPA specifically concerns FIFRA pesticide registration and reregistration in the United States, 

including all registered uses of a pesticide. The state-level Biological Assessments for APHIS 

invasive species programs are separate from any consultations conducted in association with 

pesticide registration and reregistration process.
40

The Agricultural Improvement Act of 2018 (Farm Bill) created a partnership between USDA, 

EPA, the Services, and the Council on Environmental Quality to improve the consultation 

process for pesticide registration and reregistration. USDA is committed to working to ensure 

consultations are conducted in a timely, transparent manner and based on the best available 

science. The Revised Method for National Level Listed Species Biological Evaluations of 

Conventional Pesticides provides a directionally improved path to ensuring that pesticides can 

continue to be used safely for agricultural production with minimal impacts to threatened and 

endangered species.

APHIS provided information about use of carbaryl to EPA for the FIFRA consultation for 

carbaryl. The Grasshopper Program use of carbaryl has in the past comprised substantially less 

than 1% of the percent crop treated (PCT) for rangeland use of carbaryl. This is the case for the 

reasonably foreseeable future. For rangeland, in the EPA BE, the Grasshopper Program’s very 

low usage was rounded up to <1% PCT, which gives an overestimate of rangeland acres treated 

and thus endangered species risk. APHIS use of carbaryl is even smaller compared to all uses of 

carbaryl. Further, the Grasshopper Program consults directly with the Services to ensure 

program activities do not adversely affect protected species or their critical habitat.

Comment 18

APHIS received the following comment, “The jeopardy and LAA calls for malathion and 

carbaryl should be included in the EAs and should preclude the use of these chemicals.”

APHIS consults directly with the U.S. Fish and Wildlife Service on treatments and methods. The 

U.S. Environmental Protection Agency’s on-going consultation on pesticide registration across 

all nationwide uses of program pesticides does not provide sufficiently detailed analysis or 

conclusions relevant to the Grasshopper Program.

Comment 19

APHIS received one comment that it should take into account the risk to native bees and 

butterflies from these treatments, especially those designated species of greatest conservation 

need. APHIS should constrain its treatments to take into account pollinator conservation needs, 

and improve its monitoring capability to try to understand what non-target effects actually occur 

as a result of the different treatments.

APHIS reduces the risk to native bees and pollinators through monitoring grasshopper and 

Mormon cricket populations and making pesticide applications in a manner that reduces the risk 

to this group of non-target invertebrates. Monitoring grasshopper and Mormon cricket 

populations allows APHIS to determine if populations require treatment and to make treatments 

in a timely manner reducing pesticide use and emphasizing the use of Program insecticides that 

are not broad spectrum. Historical use of Program insecticides demonstrate that diflubenzuron 

is the preferred insecticide for use. Over 90% of the acreage treated by the Program has been 

with diflubenzuron. Diflubenzuron poses a reduced risk to native bees and pollinators compared 

to liquid carbaryl and malathion applications. In addition APHIS used RAATs to treat 

approximately 99% of the acres historically treated by the Program. APHIS also uses RAATs 

that are typically below the labeled RAAT rates further reducing the amount of insecticide used 

by the program. APHIS also emphasizes the use of carbaryl bait, where applicable, as a means 
41

to suppress pest populations while protecting native bees and pollinators. These methods of 

applications have been shown to be protective of non-target invertebrates. These studies are 

referenced and summarized in the EIS.

Comment 20

APHIS received the following comment, This EA and the EIS claim that the use of untreated 

swaths will mitigate impacts to natural enemies, bees, and other wildlife. However, the width of 

the skipped swaths is not designated in advance in the EA, and there is no minimum width 

specified.

APHIS assumes that the reduced amount of pesticide that would occur using untreated swaths 

over a given treatment block will result in reduced risk to non-target organisms by reducing 

exposure. The swath width can vary based on site specific conditions, however, the end result is 

reduced pesticide exposure over a treatment area. The EIS cites studies that demonstrate that the 

use of RAATs result in higher non-target invertebrate populations compared to treatment blocks 

that did not use RAATs.

Comment 21

APHIS received two comments/recommendations about minimum swath widths, “Without 

knowing minimum (rather than maximum) swath widths that will be applied under this EA, it is 

hard to compare results from this study (Lockwood et al. 2000) to the results on non-targets 

expected under RAATS in this EA. 2). APHIS should commit to science-based methodologies to 

assess actual risk from the proposed treatments and institute minimum untreated swath widths 

wide enough to meaningfully minimize exposure to bees and other beneficials.”

Typically, APHIS employs 50% skip swaths when using RAATs. Swath widths and skips are 

determined by the type of plane doing the aerial application, the smallest being 75 feet, but the 

minimum skip swath is typically 100 feet because larger planes are often contracted.

The commenter references the work of Lockwood et al. 2000, this study looked at RAAT’s 

increasing swath widths in some instances by double skipping the untreated area. They also used 

ATV’s in their study which only have a minimum effect swath width of 30 feet. Using 

modifications presently being done in Arizona with the UTV’s ability to adjust the hopper 

height, using the same ATV spreader, the minimum effective swath width can be increased to 40 

feet, thus also increasing the untreated swath to 40 feet. APHIS uses science based 

methodologies to assess treatment related benefits or risks. APHIS has for decades funded the 

Science and Technology Research Lab in Phoenix, Arizona, which is specific to Rangeland 

Grasshopper and Mormon Cricket Program research and development. It is the only one of its 

kind in the U.S. The S&T Lab in cooperation with ASU researchers have evaluated non-target

invertebrate impacts in the past and have made recommendations to the Program side of 

APHIS.

Comment 22

APHIS received the following comment, “Although the EIS included a quantitative analysis of 

drift anticipated from ULV aerial applications to estimate deposition into aquatic areas, an 
42

analysis is not presented or available to back up the assumption that untreated areas (skipped 

swath widths) will act as refugia for natural enemies, bees, and other wildlife.”

The EIS cites studies that demonstrate that the use of RAATs result in higher non-target 

invertebrate populations compared to treatment blocks that did not use RAATs.

Comment 23

APHIS received three comments about the drift analysis described in the EA, 1) “The drift 

analysis described in the EA assumed a droplet spectra size of fine to very fine (median diameter 

= 137.5 μm). However, labels do not require a minimum droplet size for ULV applications over 

rangeland, and other uses of ULV technology for pest control assume much smaller droplet 

sizes. EPA’s (2018) Ecological Risk Assessment for diflubenzuron uses AgDrift to estimate the 

drift fraction from aerial LV applications, although it is unclear whether AgDrift is validated for 

the purposes of predicting deposition of insecticides applied using ULV technology. EPA 

assumed a volume mean diameter (VMD) of 90 μm [note that this is approximately 2/3 of the 

VMD used in the APHIS analysis]. Under EPA’s analysis, the drift fraction comprises 19% at 

150 ft.”, 2) “APHIS should disclose its quantitative analysis and the percent drift it expects--by 

distance-- into untreated swaths for each application method it proposes”, and 3) “APHIS must 

also specify in its operational procedures the use of nozzles that will result in droplet spectra that 

accord with its analysis”.

The VMD used by APHIS for diflubenzuron is the preferred median diameter used by the 

Program. APHIS recognizes that the range of droplet sizes can vary under a ULV application. 

Comment 24

APHIS received a comment that it is “unrealistic that APHIS can comply with mitigation 

measures designed to protect bees on pesticide labels “(e.g., bumble bees fly earlier and later in 

the day, diflubenzuron is toxic to developing forms, if plants are flowering, bees are active, etc.)

APHIS uses diflubenzuron at far-lower levels than allowed by the label, thereby minimizing 

risks to non-targets, such as bees. There have been several studies on diflubenzuron effects on 

bees, such as Schroeder et al. (1980) and insect growth regulator effects reviewed 

in Tasei (2001), which support the idea that the diflubenzuron levels APHIS uses for 

grasshoppers and Mormon crickets are a minimal risk to bees. APHIS also complies with any

label requirements designed to minimize impacts to pollinators.

Comment 25

APHIS received the following comment, “Except for untreated swath widths, the EA is silent on 

how it will avoid impact to pollinators. It has already been shown that within sprayed areas, risk 

quotients at expected application rates would be well above 1.0. Leaving skipped widths is also 

not a full solution at expected widths since, due to drift, untreated swaths are highly likely to be 

exposed to levels above risk quotients”.

APHIS uses diflubenzuron at far-lower levels than allowed by the label, thereby minimizing risks 

to non-targets. Additionally, APHIS commonly incorporates untreated swaths into its treatment 
43

programs, which have consistently demonstrated reduced impacts to non-target arthropods 

(Lockwood et al. (1999, 2001, 2002); Norelius and Lockwood (1999)).

Comment 26

APHIS received one comment regarding that APHIS must not ignore requirements listed on 

pesticide labels, nor make assumptions about its compliance with these when RAATS measures 

that will actually be taken are vague and unspecified.

APHIS complies with all applicable Federal and State pesticide label language when making 

pesticide treatments.

Comment 27

APHIS received the following comment: “While flexibility with these may have been 

appropriate at the EIS stage, it is not appropriate at the EA stage. APHIS must fully disclose its 

RAATS plan for each treatment in the EA, including specifying application method, chemical to 

be used, rate, and width of untreated swaths.”

RAATs are a dynamic treatment method based on the size of the treatment area, species complex, 

and density of target species. Specific details regarding RAATs cannot be determined until site 

specific data is collected during the 2020 survey season and an appropriate chemical is 

identified. Once a treatment is determined necessary, application method, untreated swath 

widths, chemical choice, and application rate are included in the bid for contracting.

Please be aware that as per conversations with BIA may preclude disclosure of Tribal 

information to the public or outside of APHIS without the consent of BIA or the Tribes. 

Individuals may request information on the specific treatment areas on Tribal Lands from the 

individual Tribal Nations or the Bureau of Indian Affairs.

Comment 28

APHIS received one comment, “To be consistent with the Pollinator-Friendly BMPs for Federal 

Lands (see Comment 7), APHIS must go beyond the general statements on the pesticide labels 

and specify more exactly how its spray plan will further reduce exposure and risk to bees.”

See Comment 25.

Comment 29

APHIS received the following comment, “The EA describes the listed species potentially 

present, some information about these species life histories and habitats, and protective measures 

for some of these species, but is silent about the consultation response from USFWS. What is the 

status of such consultation? Does USFWS concer with the Not Likely to Adversely Affect or No 

Effect calls for each of the species present within the proposed project areas? If so, what 

additional mitigation measures (if any) does USFWS suggest?”

In Wyoming, consultation with USFWS is completed as mandated by Section (7)(a)(1) of the 

Endangered Species Act (ESA). The EA includes a section that discusses APHIS’s compliance 

with the ESA and the Final EA includes the USFWS concurrence letter in Appendix 2. 
44

Comment 30

APHIS received the comment “Chlorantraniliprole is mentioned in the operating guidelines and 

in the sections describing proposed mitigations for listed species but is missing from the 

alternatives and effects sections. Chlorantraniliprole should not be used until fully analyzed.” 

Chlorantraniliprole is not proposed for use in 2020. The final EA has been updated to reflect the 

changes in the national grasshopper and Mormon cricket program.

See USFWS letters of concurrence stated in previous response.

Comment 31

APHIS received two comments concerning operationally, how will listed species’ protected 

locations be identified for ground and aerial applicators? How will such locations, buffer widths 

listed in the protective measures, and any specific instructions (i.e. use of carbaryl bait only) for 

some species be mapped and communicated to applicators? APHIS must provide to applicators a 

set of clear set of directions outlining protective measures for the listed and proposed species 

found within this project area and not burden applicators with a confusing set of directions split 

between multiple tables.

In Wyoming, after request letters are received and potential treatment areas are delineated, 

cooperative decision making begins which involves many cooperators. If additional consultation 

from USFWS is needed it is conducted prior to finalizing maps and shapefiles.

See Comment 33 and 35.

Comment 32

APHIS received one comment about pesticide specific conservation measures for each listed 

species, where appropriate, should be explicitly addressed and adopted.

Agreed upon mitigation measures address specific chemicals when conservation measures are 

warranted. These measures are agreed upon during the consultation process with the USFWS 

and are applied in the field during application.

Comment 33

APHIS received one comment that APHIS should adopt the following operational guideline 

across all site-specific EAs: “Use Global Positioning System (GPS) coordinates for pilot 

guidance on the parameters of the spray block. Ground flagging or markers should accompany 

GPS coordinates in delineating the project area as well as areas to omit from treatment (e.g., 

boundaries and buffers for bodies of water, habitats of protected species, etc.).”

In Wyoming, treatment boundaries, water bodies, sensitive sites, etc., are initially identified by 

data from land managers and land owners. These are further confirmed during nymphal surveys

and any additional sensitive sites are identified to the GIS specialist. Finalized maps are shared 

with applicators in the form of shapefiles. These shapefiles clearly show treatment boundaries, 

water buffers as per program guidelines, and other sensitive site exclusions to be treated from 
45

areas to be excluded from treatment. Communications with applicators are extensive before, 

during and after treatments. Applicators participate in daily briefings with APHIS personnel to 

review all sensitive sites. During treatments, APHIS personnel conduct environmental 

monitoring in excluded areas. Furthermore, applicators provide APHIS track-files to APHIS as 

required in the statement of work. 

Comment 34

APHIS received one comment that, “APHIS states that it has no legal obligation to manage for 

vulnerable species not on the Endangered Species List. The essential role that pollinators play in 

the conservation of listed plant species is not addressed in the EAs and makes no mention of the 

fact that there are affirmative obligations incumbent on federal agencies with regard to protection 

of pollinators, regardless of whether they are federally listed including the 2014 Presidential 

Memorandum, the National Strategy to Promote the Health or Honey Bees and Other 

Pollinators, the Pollinator Friendly BMPs for Federal Land, and the Pollinator Research Action 

Item.”

APHIS considers the role of pollinators in any consultations conducted with the USFWS

to protect federally-listed plants. Mitigation measures, such as no treatment buffers are applied 

with consideration of the protection of pollinators that are important to a particular listed plant 

species.

APHIS also implements several BMP practices in their treatment strategies that are designed to 

protect non-target invertebrates, including pollinators. APHIS minimizes insecticide 

use by using lower than labeled rates for all Program insecticides, alternating swaths during 

treatment, making only one application per season and minimizing use of liquid broad spectrum 

insecticides. APHIS also continues to evaluate new monitoring and control methods designed to 

increase the response to economically damaging populations of grasshoppers and Mormon 

crickets while protecting rangeland resources such as pollinators.

Comment 35

APHIS received one comment, “The EA does not disclose which, if any, invertebrates within the 

geographic area are listed as sensitive by federal land management agencies or as Species of 

Conservation Concern, or whether the state of Nevada designates any invertebrates as species of 

greatest conservation need.”

This EA is for Wyoming and not Nevada. Species of greatest conservation need in Wyoming are 

discussed on page 20 of the EA and are discussed during cooperative decision making 

processes.

Comment 36

APHIS received one comment regarding, the EAs protections for at risk species, including the 

monarch butterfly which is currently being assessed for listing under the Endangered Species 

Act, are practically non-existent.

Under USFWS Section 7 Act there is no requirement to consult on proposed or candidate 

species. (See USFWS letter of concurrence in Appendix 2.) However, in Wyoming when there is 
46

concern by land management agencies, federal, state, etc. it is discussed in this cooperative 

process between APHIS and landowners and land management agencies and mitigation 

measures are decided upon prior to treatment.

Comment 37

APHIS received one comment, “In the face of declining pollinator populations and the existence 

of federal directives for agencies to support and conserve pollinators and their habitat, APHIS 

must not conduct business as usual. APHIS should identify the at-risk pollinator species 

potentially present in the geographic area of the EAs and map their ranges prior to approving any 

treatment requests. Prior to treatment, APHIS should survey for presence of host plants and 

ensure that it has identified specific, actionable measures it will take to protect monarch habitat 

and the habitat of at-risk butterfly species from contamination that may occur as a result of 

exposure to treatment, such as designating a 125-ft buffer around identified habitat. Some ways 

to enact protections for at-risk species above and beyond those included in the EAs include:

● Survey for butterfly host plants and avoid any applications to host plants.

● Time pesticide applications to avoid exposure to at risk species.

● Do not apply pesticides (especially insecticides) when monarchs (adult and immature) are 

present or expected to be present.

● Avoid aerial applications.

● Avoid using malathion and liquid carbaryl.

● Include large buffers around all water sources, including intermittent and ephemeral streams, 

wetlands, and permanent streams and rivers, as well as threatened and endangered species 

habitat, honey bee hives, and any human-inhabited area. For example, Tepedino (2000) 

recommends a three-mile buffer around rare plant populations, as many of these are pollinated 

by solitary bees that are susceptible to grasshopper control chemicals.”

APHIS includes many of the proposed measures to minimize risks to non-target organisms and 

human health. These are summarized in the recent EIS. For example, no treatment buffers are 

applied to all water bodies and to areas where the public may potentially be exposed to Program 

applications. APHIS also minimizes aerial insecticide use, where possible, however site 

conditions may dictate the need for aerial treatments. APHIS minimizes use of liquid carbaryl 

and malathion which is reflected in the historical use for both insecticides. Diflubenzuron has 

been the preferred insecticide for making Program suppression treatments. In addition APHIS 

has incorporated the use of RAATS in the Program as a means to reduce insecticide use 

providing reduced risk while meeting the goal of suppression. APHIS continues to research and 

develop new techniques for management of grasshopper and Mormon cricket populations.

Comment 38

APHIS received the following comment, “While the mitigations that are identified for aquatic 

habitats in the EAs are heartening, APHIS should include monitoring for the presence and health 

of mussels in streams that traverse or are adjacent to treatment areas as part of its monitoring 

strategy.”

APHIS conducts environmental monitoring related to Program treatments. Monitoring is 

typically done adjacent to sensitive habitats, including aquatic habitats, to determine pesticide 

residues. These data can be used to determine risk to non-target organisms based on available 

toxicity data.
47

Comment 39

APHIS received the following comment, “To protect freshwater mussels, APHIS should use the 

same buffers agreed to in the national consultation with NMFS to protect listed salmon to protect 

freshwater mussels.”

APHIS agrees that freshwater mussels should be protected, as well as other aquatic organisms, 

and uses ground and aerial application no treatment buffers adjacent to all aquatic habitats. In 

addition, APHIS uses reduced rates of Program insecticides compared to current labeled rates. 

These mitigation measures are beyond label requirements for protection of aquatic habitats. The 

intent of these buffers is to reduce off-site drift and runoff of Program insecticides to aquatic 

habitats.

Comment 40

APHIS received the following comment, “The EAs do not discuss water bodies of anthropogenic 

origin, such as stock tanks or stock ponds, nor any buffers that will be observed to prevent 

pesticide overspray or drift into these habitats.”

In Wyoming, all stock tanks and stock ponds are buffered for applications.

Comment 41

APHIS received the following comment, “APHIS should recognize the potential for stock 

pond/tanks to contribute significantly to the diversity of aquatic invertebrates in rangelands.”

See previous response. All bodies of water are buffered according to the APHIS Guidelines in 

Appendix 1 of the EA.

Comment 42

APHIS received the following comment, “APHIS should identify and map all stock tanks/ponds 

and specify a buffer around stock ponds/tanks from chemical treatment at least equivalent to that 

specified for wetlands, in order to protect aquatic diversity.”

All bodies of water are buffered according to APHIS Guidelines in Appendix 1 of the EA. In 

Wyoming, locations of stock tanks are provided to APHIS by land owners and land managers to 

be used in the field during delimiting surveys and treatment planning. Tribal stock tank 

locations are provided to APHIS but are not to the public. Tribal maps can be provided from the 

BIA.

Comment 43

APHIS received one comment, “APHIS’ reactive strategy includes no mention of what is most 

sorely needed: cooperation and planning with land managers to take appropriate steps to prevent 

the types of grasshopper and cricket outbreaks that are now dealt with by chemical controls.”

APHIS is not a land management agency, but encourages IPM through past and current 

research and will continue to do so.
48

APHIS supports the use of IPM in the management of grasshoppers and Mormon Crickets. 

APHIS provides technical assistance to Federal, Tribal, State and private land managers 

including the use of IPM. However, implementation of on-the-ground IPM activities is limited to

land management agencies and Tribes, as well as private land owners. In addition, APHIS’ 

authority under the Plant Protection Act is to treat Federal, State and private lands for 

grasshoppers and Mormon cricket populations. APHIS’ technical assistance occurs under each 

of the three alternatives proposed in the EIS.

In addition to providing technical assistance, APHIS completed the Grasshopper Integrated Pest 

Management (GIPM) project, which is discussed in more detail on page 21 of this EIS. One of 

the goals of the GIPM is to develop new methods of suppressing grasshopper and Mormon 

cricket populations that will reduce non-target effects. RAATs are one of the methods that has 

been developed to reduce the amount of pesticide used in suppression activities, and is a 

component of IPM. APHIS continues to evaluate new suppression tools and methods for 

grasshopper and Mormon cricket populations, including biological control, and as stated in the 

EIS, will implement those methods once proven effective and approved for use in the United 

States.

Comment 44

APHIS received one comment: “Emphasizing cultural techniques through appropriate grazing 

management could help to minimize pesticide application and allow natural enemies to regulate 

grasshopper and Mormon cricket populations to the greatest extent possible. While more 

research is needed to develop species- and region-specific management treatments that use 

alternatives to pesticides (Vermeire et al. 2004), there is likely enough data to employ cultural 

techniques now.”

APHIS supports the use of IPM in the management of grasshoppers and Mormon Crickets. 

APHIS provides technical assistance to Federal, Tribal, State and private land managers 

including the use of IPM, including cultural techniques. However, implementation of on-theground IPM activities is limited to land management agencies and Tribes, as well as private land 

owners. In addition, APHIS’ authority under the Plant Protection Act is to treat Federal, State 

and private lands for grasshoppers and Mormon cricket populations.

Comment 45

APHIS received one comment that, “APHIS must elevate the expectation of preventative 

approaches in its cooperative agreements with other land management agencies. APHIS can 

collaborate with agencies (such as the Natural Resource Conservation Service (NRCS), the Farm 

Service Agency (FSA), and State Extension program) to facilitate discussion and disseminate

information to ranchers about preventative measures that can be taken and alternatives to 

pesticide use.”

APHIS supports the use of IPM in the management of grasshoppers and Mormon Crickets. 

APHIS provides technical assistance to Federal, Tribal, State and private land managers 

including the use of IPM, including cultural techniques. However, implementation of on-theground IPM activities is limited to land management agencies and Tribes, as well as private land
49

owners. In addition, APHIS’ authority under the Plant Protection Act is to treat Federal, State 

and private lands for grasshoppers and Mormon cricket populations.

APHIS has maintained cooperative relationships with state and federal land managers as well as 

private landowners and Indian tribes for decades. Those relationships have allowed APHIS to 

provide consistent and continual recommendations on land management practices designed 

to mitigate the damage from orthopteran infestations.

Comment 46

APHIS received on comment that, “APHIS and/or collaborating agencies should investigate and 

implement opportunities to incentivize healthy range management practices.”

As part of its ongoing IPM strategy to manage grasshoppers and Mormon cricket outbreaks, 

APHIS collaborates with scientists and land managers focused on rangeland health.

Comment 47

APHIS received one comment that, “APHIS and its partners should be approaching the problem 

by keeping a focus on the potential to reduce grasshopper carrying capacity by making the 

rangeland environment less hospitable for the pests. APHIS must not take a limited view of its 

role and responsibilities, and should utilize any available mechanism to require land management 

agencies to diminish the severity, frequency and duration of grasshopper outbreaks by utilizing 

cultural management actions. Memoranda of Understanding (MOUs) should be examined and 

updated to ensure that land management agencies are accountable in utilizing cultural techniques 

to diminish the carrying capacity of pest species.

APHIS supports the use of IPM in the management of grasshoppers and Mormon Crickets. 

APHIS provides technical assistance to Federal, Tribal, State and private land managers 

including the use of IPM. However, implementation of on-the-ground IPM activities is limited to 

land management agencies and Tribes, as well as private land owners. In addition, APHIS’ 

authority under the Plant Protection Act is to treat Federal, State and private lands for 

grasshoppers and Mormon cricket populations.

Comment 48

APHIS received a comment, “Longer-term strategic thinking should include:

●Prevent conditions that allow pest populations to survive and reproduce.

● Employ diverse management techniques (e.g., biological, physical, and cultural).

● Select pesticides to minimize risks to non-target organisms.

● Implement frequent and intense monitoring to identify populations that can be controlled with 

small ground-based pesticide application equipment.

● Monitor sites before and after application of any insecticide to determine the efficacy of the 

pest management technique as well as if there is an impact on water quality or non-target 

species.”

APHIS currently monitors for grasshopper and Mormon cricket populations. These measures 

are employed to allow APHIS to respond with treatment, where warranted, treating the smallest 

area possible and if practical using ground-based equipment. APHIS, due to its monitoring 

efforts, has been able to rely on diflubenzuron as the primary insecticide used in the Program.
50

Diflubenzuron is a more selective insecticide compared to carbaryl and malathion posing less 

risk to non-target organisms. APHIS also uses environmental monitoring to assess application 

success and to determine if Program insecticides are reaching sensitive habitats, including 

aquatic habitats. APHIS supports the use of IPM in the management of grasshoppers and 

Mormon Crickets. APHIS provides technical assistance to Federal, Tribal, State and private 

land managers including the use of IPM. However, implementation of on-the-ground IPM

activities is limited to land management agencies and Tribes, as well as private land owners. In 

addition, APHIS’ authority under the Plant Protection Act is to treat Federal, State and private 

lands for grasshoppers and Mormon cricket populations. APHIS continues to research and 

develop new methods for assessing and controlling grasshopper and Mormon cricket 

populations that can be incorporated into IPM practices. 

Comment 49

APHIS received one comment that, “The EAs do not make mention of any specific protections to 

be accorded to special status lands such as Wilderness areas, Wilderness study areas, Research 

Natural Areas, National Wildlife Refuges, and designated or proposed Areas of Critical 

Environmental Concern. These special status areas have been designated for specific purposes 

and generally discourage human intervention with the natural ecosystem. Grasshopper 

suppression should not be undertaken in such areas.”

APHIS does not make treatments on lands of special status without a request from that agency 

and an evaluation of the whether treatments are necessary. Additional protection measures for 

these types of lands are established by the agency requesting treatment and are followed by 

APHIS.

Comment 50

APHIS received the comment “The EA cites a 1995 Biological Opinion with US Fish and 

Wildlife on listed species, but makes no mention of a newer Biological Opinion or letter of 

concurrence for the newer chemical diflubenzuron which is listed as one of the active ingredients 

allowed under the preferred alternative.”

The 1995 Biological Opinion is the most current between APHIS and USFWS on a national 

level. Local and site specific consultations take place annually in Wyoming. The concurrence 

letter received this year from USFWS can be found in Appendix 2. 

Comment 51

APHIS received the comment that the EA does not adequately address the essential role of 

pollinators in the conservations of listed plant species.

The EIS analyzed concerns for pollinators in regards to the grasshopper program, underwent 

the NEPA process and had been finalized. The EA is tiered to the EIS.

Comment 52

APHIS received the following comment “We appreciate that public notice of this site-specific 

EA and its comment period was posted at the APHIS website. It does not appear to have been the 

practice to post the Draft EAs in the last several years, but limiting public notice is contrary to 

the spirit of the NEPA process. Grasshopper suppression efforts are of more than local concern 
51

and as federal actions, should be noticed properly, i.e. beyond local stakeholder audiences, local 

newspapers, etc. We recommend that, in the future, notice of open public comment periods for 

all site-specific EAs for grasshopper suppression be posted in the Federal Register, and 

documents made available for review at regulations.gov and at the APHIS grasshopper 

website.”

Public involvement under the CEQ Regulations for Implementing the Procedural Provisions of 

NEPA distinguishes federal actions with effects of national concern from those with effects 

primarily of local concern (40 CFR 1506.6). Our EIS process for the grasshopper and Mormon 

cricket suppression program was published in the Federal Register (APHIS-2016-0045), and met 

all applicable notice and comment requirements for a federal action with effects of national 

concern. This process provided individuals and national groups the ability to participate in the 

development of alternatives and provide comment. Our subsequent state-based actions have the 

potential for effects of local concern, and we publish them according to the provisions that apply 

to federal actions with effects primarily of local concern. This includes the USDA APHIS NEPA 

Implementation Procedures, which allows for EAs and FONSIs where the effects of an action are 

primarily of regional or local concern to normally provide publication in a local or area

newspaper of general circulation (7 CFR 372.7(b)(3)). These publications provide potentially 

locally-affected individuals an additional opportunity to provide input into the decision-making 

process. Some states also provide additional opportunities for local public involvement, such as 

public meetings.

Comment 53

APHIS received the following comments, “The Draft Environmental Assessments Frustrate 

Public Participation.” and “APHIS frustrated public participation by failing to inform interested 

parties of the existence of the EAs.”

“Scoping” is the process APHIS uses through which the agency and the public identify 

alternatives and issues to be considered during the development of a grasshopper or Mormon 

cricket suppression program. Scoping was helpful in the preparation of the draft Environmental 

Assessments (EAs). The process can occur formally and informally through meetings, 

conversations, or written comments from individuals and groups.

Prior to the treatment season, APHIS conducted meetings or provided guidance for public 

participation in the decision making process. In addition, APHIS notified Federal, State and BIA

land managers and private landowners of the potential for grasshopper and Mormon cricket 

outbreaks on their lands.

Comment 54

APHIS received the following comment, “APHIS did not providing information for the 

submission of public comments including where and when to submit comments by.”

APHIS works to inform all interested parties about draft EA’s for comment. When an interested 

party asks to be informed, APHIS ensures contact information is added to the list of interested 

stakeholders. Each local office works to inform interested parties of the availability of an EA for 

comment. Any omission of an interested party is not intentional.
52

A notice of public comment was sent to all parties who expressed interest in the past or at public 

meetings in addition to the local newspapers, tribal nations, federal and state cooperators. A 

letter of notice clearly defining the 30 day comment period and the contact information of local 

APHIS personnel responsible for drafting the state EAs was also sent out to the respective 

parties.

Comment 55

APHIS received the following comment, “APHIS frustrated public participation by failing to 

inform interested parties of the existence of the EA, by not providing information for the 

submission of public comments including where and when to submit comments by, limiting 

public notice to local papers, and providing a short public comment period during this COVID19 pandemic.”

Public involvement under the CEQ Regulations for Implementing the Procedural Provisions of 

NEPA distinguishes federal actions with effects of national concern from those with effects 

primarily of local concern (40 CFR 1506.6). Our EIS process for the GMC program was 

published in the Federal Register (APHIS-2016-0045), and met all applicable notice and 

comment requirements for a federal action with effects of national concern. This process 

provided individuals and national groups the ability to participate in the development of 

alternatives and provide comment. Our subsequent state-based actions have the potential for 

effects of local concern, and we publish them according to the provisions that apply to federal 

actions with effects primarily of local concern. This includes the USDA APHIS NEPA 

Implementation Procedures, which allows for EAs and FONSIs where the effects of an action are 

primarily of regional or local concern to normally provide publication in a local or area 

newspaper of general circulation (7 CFR 372.7(b)(3)). These publications provide potentially 

locally-affected individuals an additional opportunity to provide input into the decision-making 

process. Some states also provide additional opportunities for local public involvement, such as 

public meetings.

Comment 56

APHIS received the following comments, “APHIS provided a short public comment period 

during this COVID-19 pandemic.” “The 30 day comment deadline for the Draft EAs is wholly 

inappropriate during the current COVID-19 pandemic, where both staff and members of the 

concerned public have limited capacity, given the challenges associated with a global pandemic 

including but not limited to increased childcare demands, illness, etc.”

The comment period was in accordance with CEQ regulations, 40 C.F.R. § 1501.4(e) (2), in 

determining whether to prepare an environmental impact statement the Federal agency shall: (e) 

Prepare a finding of no significant impact, if the agency determines on the basis of the 

environmental assessment not to prepare a statement. (2) In certain limited circumstances, which 

the agency may cover in its procedures under § 1507.3, the agency shall make the finding of no 

significant impact available for public review (including State and area-wide clearinghouses) for 

30 days before the agency makes its final determination whether to prepare an environmental 

impact statement and before the action may begin. CEQ guidance also notes: When preparing 

an EA, the agency has discretion as to the level of public involvement. The CEQ regulations state 

that the agency shall involve environmental agencies, applicants, and the public, to the extent 
53

practicable, in preparing EAs. Sometimes agencies will choose to mirror the scoping and public 

comment periods that are found in the EIS process. In other situations, agencies make the EA 

and a draft FONSI available to interested members of the public. APHIS would have 

considered extending the comment period if there had been a reason to believe that additional 

substantive issues remained, or that the pandemic itself created new issues.

Comment 57

APHIS received the following comment, “The Draft EAs also limit public participation by 

failing to provide contact information for the submission of written or electronic comments.”

The local offices send out public notices to a list of stakeholders that they have collected over the 

years and also announced the open comment period in the local media. Those notices have the 

link for the EA’s and the point of contact. The cover page of the EA has contact information 

included. In an attempt to be more transparent APHIS has also placed Program EA’s on to 

the APHIS website for the public to access. When an interested party asks to be informed, APHIS 

ensures their contact information is added to the list of interested stakeholders. Each local office 

works to inform interested parties of the availability of an EA for comment. Any omission of an 

interested party is not intentional. 

Comment 58

APHIS received the following comment, “Nowhere on the webpage for the Draft Environmental 

Assessment Rangeland Grasshopper and Mormon Cricket Suppression Program is there any 

information on where to submit comments.”

The local offices send out public notice to a list of stakeholders that they have collected over the 

years and they also announce the open comment period in the local media. Those notices have 

the link for the EA’s for comment and the point of contact. In an attempt to be more 

transparent APHIS has also placed Program EA’s on its website. When an interested party asks 

to be informed, APHIS ensures their contact information is added to the list of interested 

stakeholders. Each local office works to inform interested parties of the availability of an EA for 

comment. Any omission of an interested party is not intentional. (See Previous Response).

Comment 59

APHIS received the following comment, “Staff for USDA-APHIS that have been involved with 

the environmental review for this program were unable to readily provide information for the 

submission of public comment.”

The local offices send out public notice to a list of stakeholders that they have collected over the 

years and they also announce the open comment period in the local media. Those notices have 

the link for the EA’s for comment and the point of contact. In an attempt to be more 

transparent, we have put all of our EA’s on to the website for people to access. When an 

interested party asks to be informed APHIS ensures their contact information is added to the list 

of interested stakeholders. Each local office works to inform interested parties of the availability 

of an EA for comment. Any omission of an interested party is not intentional. The cover page of 

the EA has contact information included.
54

APHIS is not aware of the direct personnel communication cited by the commenter. APHIS

personnel are engaged in a wide variety of activities to protect American agriculture and not 

every staff member is completely informed about the details of the Grasshopper Program NEPA 

compliance procedures.

Comment 60

APHIS received the following comment, “there is no information on when the comment period 

opened or closed on the EAs provided on the webpage.”

The local offices send out public notice to a list of stakeholders that they have collected over the 

years and they also announce the open comment period in the local media. Those notices have 

the link for the EA’s for comment and the point of contact. The cover page of the EA has contact 

information included. In an attempt to be more transparent, we have put all of our EA’s on to the 

website for people to access. When an interested party asks to be informed, APHIS ensures their

contact information is added to the list of interested stakeholders. Each local office works to 

inform interested parties of the availability of an EA for comment. Any omission of an interested 

party is not intentional.

Comment 61

APHIS received the following comment, “With the EA dated March 11, 2020, a reasonable 

person could have easily concluded that a 30 day comment period ended on April 11, 2020 rather 

than the April 24, 2020 comment deadline.”

See previous comment response.

Comment 62

APHIS received the following comment, “APHIS has failed to comport with NEPA’s threshold 

requirements.”

APHIS did not fail to perform NEPA’s threshold requirements for public outreach and 

engagement, but rather exceeded them. See previous comments concerning how APHIS informed 

interested parties of the availability of EAs for public comment, including public meetings, where 

to send comments, and the closing date for the comment period. See response to previous 

comment.

Comment 63

APHIS received the following comment, “The Draft EAs further limit public participation by 

failing to post notices in the Federal Register or on regulations.gov, unlike earlier versions of the 

environmental review.”

APHIS further involves the public in the scoping process by the publication of notices of 

availability for EAs and a Findings of No Significant Impact (FONSIs). When an individual State 

level EA is written, a notice is published in the legal section of the local newspaper, advertising 

the availability of the EA during an open comment period. The notices published in local 

newspapers was conducted in accordance with APHIS’ NEPA Implementation Procedures, 

372.7 (b)(3), Notification of the availability of environmental assessments and findings of no 

significant impact for proposed activities will be published in the FEDERAL REGISTER, unless 
55

it is determined that the effects of the action are primarily of regional or local concern. Where 

the effects of the action are primarily of regional or local concern, notice will normally be 

provided through publication in a local or area newspaper of general circulation and/or the 

procedures implementing Executive Order 12372, “Intergovernmental Review of Federal 

Programs.”

Public involvement under the CEQ Regulations for Implementing the Procedural Provisions of 

NEPA distinguishes federal actions with effects of national concern from those with effects 

primarily of local concern (40 CFR 1506.6). Our EIS process for the GMC program was 

published in the Federal Register (APHIS-2016-0045), and met all applicable notice and 

comment requirements for a federal action with effects of national concern. This process 

provided individuals and national groups the ability to participate in the development of 

alternatives and provide comment. Our subsequent state-based actions have the potential for 

effects of local concern, and we publish them according to the provisions that apply to federal 

actions with effects primarily of local concern. This includes the USDA APHIS NEPA 

Implementation Procedures, which allows for EAs and FONSIs where the effects of an action are 

primarily of regional or local concern to normally provide publication in a local or area 

newspaper of general circulation (7 CFR 372.7(b)(3)). These publications provide potentially 

locally-affected individuals an additional opportunity to provide input into the decision-making 

process. Some states also provide additional opportunities for local public involvement, such as 

public meetings.

Comment 64

APHIS received the following comment, “[The Center for Biological Diversity] have 

been informed that there was notice in local newspapers. This local notice is insufficient as it 

excludes countless other interested parties.”

See previous response.

Comment 65

APHIS received the following comment, “APHIS has failed to meet NEPAs requirements for 

public involvement in these EAs.”

APHIS also notes CEQ guidance for public involvement in the NEPA process of agencies, “A 

Citizen’s 12 Guide to the NEPA” states: “When preparing an EA, the agency has discretion as 

to the level of public involvement. The CEQ regulations state that the agency shall involve 

environmental agencies, applicants, and the public, to the extent practicable, in preparing EAs. 

Sometimes agencies will choose to mirror the scoping and public comment periods that are 

found in the EIS process. In other situations, agencies make the EA and a draft FONSI available 

to interested members of the public”.

Comment 66

APHIS received the following comment, “the range of alternatives offered by APHIS is 

inadequate and confusing.”
56

APHIS structured and analyzed the risk of the substantial program alternatives available to the 

agency. Alternatives, including those excluded from further analysis, were discussed in the final 

EIS.

Comment 67

APHIS received the following comment, “[The alternatives] are outlined as, “No Suppression 

Program,” “Insecticide Applications at Conventional Rates or Reduced Agent Area Treatments 

with Adaptive Management Strategy (Preferred Alternative)” and “Experimental 

Treatments.” While the RAATs are an improvement over conventional approval rates, this 

alternative should actually be two, one, Insecticide Applications at Conventional Rates and two, 

Reduced Agent Area Treatments with Adaptive Management Strategy. Lumping the two 

together means that supporting this alternative could mean pesticide application at conventional 

rates without RAATs. APHIS must break these into different alternatives.”

The EA states “Under Alternative A, the No Action alternative (here called the No Suppression 

Alternative), APHIS would not conduct a program to suppress grasshopper infestations. Under 

this alternative, APHIS may opt to provide limited technical assistance, but any suppression 

program would be implemented by a Federal land management agency, a State agriculture 

department, a local government, or a private group or individual.”

Under Alternative B, the Preferred Alternative, APHIS would manage a grasshopper treatment 

program using potentially any of the three approved pesticides and application 

methods described in the EA Alternative B to suppress outbreaks. The grouping of conventional 

methods and pesticide rates with the more commonly used RAATs procedures reflects the variety 

of approaches that the agency may need depending on treatment specific circumstances.

Comment 68

APHIS received the comment, “APHIS does not adequately explain why the “Experimental 

Treatments” alternative is not preferred, despite the fact that it is described in far greater detail 

than the other alternatives.” 

In the Wyoming EA this section is titled Research Treatment Alternative. The Research 

Treatment Alternative is for testing new chemicals and treatment strategies for possible future 

incorporation into the program alternatives and is completed by the Science and Technology 

branch of APHIS PPQ. These Research Treatments are typically conducted on private property 

with permission and are smaller in scope to test various treatment strategies. The Research 

Treatment alternative is not used to suppress grasshoppers as requested by landowners and land 

managing agencies.

Comment 69

APHIS received the following comment, “APHIS does not include an alternative that utilizes 

Integrated Pest Management.”

APHIS technical guidance is part of each alternative proposed, and is not unique to any one 

alternative. An example of APHIS technical guidance is the agency’s work on integrated pest 
57

management (IPM) for the grasshopper program. IPM for grasshoppers includes biological 

control, chemical control, rangeland and population dynamics, and decision support tools.

APHIS has funded the investigation of various integrated pest management (IPM) strategies for 

the grasshopper program. Congress established the Grasshopper Integrated Pest Management 

(GIPM) to study the feasibility of using IPM for managing grasshoppers.

The major objectives of the APHIS GIPM program were to: 1) manage grasshopper populations 

in study areas, 2) compare the effectiveness of an IPM program for rangeland grasshoppers with 

the effectiveness of a standard chemical control program on a regional scale, 3) determine the 

effectiveness of early sampling in detecting developing grasshopper infestations, 4) quantify 

short- and long-term responses of grasshopper populations to treatments, and 5) develop and 

evaluate new grasshopper suppression techniques that have minimal effects on non-target 

species (Quinn, 2000). The results for the GIPM program have been provided to managers of 

public and private rangeland including ways to manage grasshopper populations in the longterm, such as livestock grazing methods and cultural control by farmers.

APHIS issued the GIPM User Handbook describing biological control, chemical control, 

environmental monitoring and evaluating, modeling and population dynamics, rangeland 

management, decision support tools, and future directions.

Federal and State land management agencies, State agriculture departments, and private groups 

or individuals may carry out a variety of preventative IPM strategies that may reduce the 

potential for grasshopper outbreaks. Some of these activities include grazing management 

practices, cultural and mechanical methods, and prescribe-burning of rangeland areas. These 

techniques have been tried with varying success in rangeland management, and some have been 

associated with the prevention, control, or suppression of harmful grasshopper populations on 

rangeland.

Regardless of the various IPM strategies taken, the primary focus of the risk analysis contained 

in the EAs is on the potential impacts from chemical treatments needed during an outbreak of 

economic importance. While APHIS provides technical expertise regarding grasshopper 

management actions, the responsibility for implementing most land management practices lies 

with other Federal (i.e., BIA, BLM, and USDA’s FS), State, and private land managers.

The final EA will be updated to reflect APHIS support for IPM strategies in the grasshopper and 

Mormon cricket suppression program.

Comment 70

APHIS received the following comment, “Given that much of APHIS’s work on grasshopper and 

Mormon cricket suppression is on lands managed by DOI or USDA or adjacent to federal public 

lands in Wyoming, it only makes sense that it would conform to their IPM mandates in these 

EAs.” 

See previous response. APHIS supports the use of IPM to prevent grasshopper outbreaks on or 

near Federal lands. These actions are and should continue to be considered by agencies as part 
58

of proper land management. APHIS treatments are a component of the IPM strategies that may 

be employed by Federal land management agencies. APHIS also adheres to any restrictions 

proposed by Federal or State land management agencies that may be part of their IPM 

strategies. 

Comment 71

APHIS received the following comment, “APHIS must adopt an alternative that harmonizes its 

mandates in regard to grasshoppers and Mormon crickets with the IPM mandates of the federal 

lands that it operates on.”

See previous response. A Memorandum of Understanding between land management agencies, 

i.e., the Department of Interior’s Bureau of Indian Affairs and Bureau of Land Management, and 

USDA’s Forest Service, indicates that while APHIS provides technical expertise, namely advice, 

regarding grasshopper management actions, the responsibility for implementing most land 

management practices, including IPM measures, lies with other Federal (i.e., BIA, BLM, and 

USDA’s FS), State, and private land managers (page 32 of the 2019 EIS).

Comment 72

APHIS received the following comment, “APHIS must enlist IPM experts to craft an alternative 

that is land-use and pest-specific, using the minimum level of pest suppression necessary, relying 

on prevention, avoidance, monitoring, and suppression techniques in order to decrease pest 

pressure with the least harmful controls possible.”

See previous comment response.

Comment 73

APHIS received the following comments, “APHIS must conduct an adequate analysis of human 

health effects”, “The EA’s fail to take a hard look at the impacts of the proposed action on 

human health in Nevada. APHIS simply makes conclusory statements and appears to be 

attempting to minimize the threats” and “APHIS is proposing to use very dangerous chemicals 

that can cause a variety of significant impacts to human health.”

The commenter has suggested the Wyoming Grasshopper Program EA should have taken a hard 

look at human health effects in Nevada resulting from grasshopper suppression activities. The 

risk analysis in the EA is tiered to the two Environmental Impact Statements (2002 and 2019) 

and the four Human Health and Ecological Risk Assessments as described in sections I.C. About 

this Process, II.A. Alternatives (where an internet link to the more in-depth risk analysis 

documents is provided on page 7), in the second paragraph of section IV. Environmental 

Consequences (a link is also provided there), and many other locations in the EA.

Adherence to label requirements and additional Program measures designed to reduce exposure 

to workers (e.g., PPE requirements include long-sleeved shirt and long pants and shoes plus 

socks) and the public (e.g., mitigations to protect water sources, mitigations to limit spray drift, 

and restricted-entry intervals) result in low health risk to all human population segments.
59

Comment 74

APHIS received the following comment, “APHIS states that “[n]o treatment will occur over 

congested areas, recreation areas, or schools and if appropriate, a buffer zone will be enacted and 

enforced. While APHIS may believe this to be the case, it can not claim to know all the areas 

where people congregate or recreate in Wyoming, and it provides no information on what kinds 

of buffer zones it would enact and enforce even if it did”.

The grasshopper program is a rangeland program and normally conducted in a mixture of 

federal lands, state lands and private lands where people are not likely to congregate or 

recreate. Open communications between applicators and APHIS personnel about treatment 

occur throughout the treatment to avoid any unforeseen congregations or bystanders. 

Landowners and land managers whose lands fall within the treatment area are aware of the 

treatment activities. 

Comment 75

APHIS received the following comment, “APHIS’s failure conduct any analysis of their impacts 

to human health is a far cry from the level of analysis demanded by NEPA and basic due care for 

public health.” 

See responses to comment 73. APHIS prepared and published separate Final Human Health and 

Ecological Risk Assessments for all the pesticides used by the Grasshopper Programs 

(November 2019). These documents were incorporated by reference into the draft EA.

Comment 76

APHIS received the following comment, “APHIS fails to look at the effects of the proposed 

action on migratory birds.”

Executive Order 13186 directs Federal agencies taking actions with a measurable negative 

effect on migratory bird populations to develop and implement a Memorandum of Understanding 

with the USFWS that promotes the conservation of migratory bird populations. On August 2, 

2012, a Memorandum of Understanding between APHIS and the USFWS was signed to facilitate 

the implementation of this Executive Order.

Specifically to the grasshopper and Mormon cricket program, APHIS evaluated potential 

impacts to birds in the final EIS and associated human health and ecological risk assessments.

These documents are incorporated by reference into the final EA.

Comment 77

APHIS received the following comment, “APHIS needs to take a hard look at the impacts of the 

proposed action, including direct and indirect effects.”

The EA incorporated the analysis from the EIS and associated human health and ecological risk 

assessments into the analysis. The EIS, and in particular, the risk assessments evaluated 

potential indirect effects to non-target organisms, relying on available toxicity data and 

estimates of risk. 
60

Comment 78

APHIS received the following comments, “A direct effect of not spraying insecticides is 

abundant food for migratory birds. Conversely, a direct effect of spraying is reduced abundance 

of food for insectivorous migratory birds. Another potential direct effect of insecticide spraying 

is poisoning. An example of an indirect effect is the cumulative effect of continuous low level 

pesticide exposure from numerous sites over many years. APHIS must take a hard look at all 

these impacts” and “APHIS says that it will strive to reduce populations below levels 

encountered in non-outbreak years, but whether APHIS will actually be able to achieve this is 

unknown, and also fails to include consideration of the fact that migratory birds may rely on the 

boom and bust cycles of grasshopper outbreaks.”

The routine use of Reduced Area Agent Treatment (RAAT) procedures results in the temporary 

reduction of insects that birds prey upon within the treated swaths. This indirect effect is 

mitigated by the unchanged abundance of prey in nearby untreated swaths. The EIS analyzes the 

toxicological effects of Grasshopper applied insecticides on birds (carbaryl p. 42-43, 

diflubenzuron p.50-52, malathion p.61-63, and chlorantraniliprole p.75). The EIS also describes 

the potential effects on birds caused by loss of prey (diflubenzuron p. 52, malathion p. 63, 

generally p. 88-89).

Comment 79

APHIS received the following comment, “APHIS’s handling of impacts to non-target species 

and species of concern wholly fails to meet NEPA’s requirement that the agency take a hard look 

at the impacts of its proposed action.”

APHIS prepared and published separate Final Human Health and Ecological Risk Assessments 

for all the pesticides used by the grasshopper and Mormon cricket suppression 

program (November 2019). The EIS and risk assessments evaluated available effects data and 

risk to non-target species. These documents are incorporated by reference into the final EA. The 

risk assessments provided the basis for summary statements in the EA that is tiered to the EIS.

The USFWS defines "Species of concern" is an informal term that refers to those species which 

may require some conservation actions but which are not threatened with extinction. The 

conservation actions needed will vary depending on the health of the populations and types and 

degree of threats. At one extreme, there may only need to be periodic monitoring of populations 

and threats to the species and its habitat. At the other extreme, a species eventually may require 

listing as a Federal threatened or endangered species and become the subject of a Federal 

recovery program. Species of concern receive are not provided legal protection under the 

Endangered Species Act, and the use of the term does not necessarily mean that the species will 

eventually be proposed for listing as a threatened or endangered species. Based on USFWS 

funding and staffing levels discussions with APHIS about species of concern may occur during 

broader ESA consultations and result in specific protections measures observed by the 

Grasshopper Program.

Comment 80

APHIS received the following comment, “The EA cannot be finalized until APHIS actually takes 

a hard look at the impacts on non-target and species of concern.”
61

APHIS prepared and published separate Final Human Health and Ecological Risk Assessments 

for all the pesticides used by the grasshopper and Mormon cricket suppression program 

(November 2019). The EIS and risk assessments evaluated available effects data and risk to nontarget species. These documents are incorporated by reference into the final EA. The risk 

assessments provided the basis for summary statements in the EA that is tiered to the EIS.

Under USFWS Section 7 Act there is no requirement to consult on sensitive species. See USFWS 

letter of concurrence in Appendix 2. 

Comment 81

APHIS received the following comment, “APHIS must consider the impacts of the proposed 

action on sensitive or culturally important species.”

APHIS prepared and published separate Final Human Health and Ecological Risk Assessments 

for all the pesticides used by the Grasshopper Programs (November 2019). See response to 

previous comment. 

Comment 82

APHIS received the following comment, “While pollinators are mentioned, impacts to them are 

not actually analyzed. Grasshopper spraying season is precisely when bees are flying”

and “Insecticide spraying done in the wrong place at the wrong time could have the tragic and 

unintended consequence of out an entire population of a species, or even driving extinct a rare 

species, perhaps even one that has never been named. Native bees remain understudied and 

underappreciated, despite the hugely important impacts they have on ecosystem function.”

APHIS works with BIA, Federal and State land managers and their local biologists, natural 

resource specialists, and range conservationists to implement measures that reduce risks of 

Program treatments to native bees. These measures may include reduced insecticide applications 

associated with RAATS, avoidance measures and use of carbaryl bait, where applicable. 

APHIS also prepared and published separate Final Human Health and Ecological Risk 

Assessments for all the pesticides used by the Grasshopper Programs (November 2019). The risk 

assessments summarized available effects data for non-target species including pollinators.

Comment 83

APHIS received the following comment, “The EAs have not adequately analyzed the cumulative 

impacts of the program with other governmental or private entity actions.”

APHIS discussed the potential of overlapping chemical treatments in the areas where outbreaks 

of grasshoppers have occurred or could occur in the future in the cumulative impacts section of 

the draft EIS, from page 79 to 83. It is unlikely there would be significant overlap between 

APHIS programs and the grasshopper program and coordinated treatments would mitigate 

impacts if there is ever overlap; current label and mitigations minimize significant exposure of 

soil, water, and air to Program insecticides; grasshopper chemical treatments are not expected 

to persist or bioaccumulate in the environment; and, there is a lack of significant routes of 

exposure (page 82 to 83 of draft EIS).
62

We are unaware of any retreatment that would occur in an area where APHIS has conducted 

a treatment. Generally, the land that APHIS treats is a hybrid of BLM rangeland and requesting

landowners leasing land for grazing. Private landowners do not actively manage that land 

and, therefore, are not expected to be making any other types of chemical treatments.

Although APHIS is unaware of any, BLM could potentially do herbicide treatments in areas we 

treat, but they would not treat for GHMC. 

Comment 84

APHIS received the following comment, “The EA does not take into account the background 

level of exposure to humans and animals from pesticides and other pollutant sources that exist in 

the environment from other actions or the synergistic effects of the enhanced toxicity that many 

mixtures exhibit.”

The commenter assumes that the rangeland in Wyoming which is covered by the Draft EA WY20-01 has been exposed to pesticides and pollutants and have a synergistic effect which 

enhances toxicity to the environment. The land managers that manage the areas covered in the 

EAs, document all pesticide applications. The activities, or lack thereof, are discussed in the 

cumulative impacts section of the final EA.

Comment 85

APHIS received the following comment, “[the EA] does not account for the range of cumulative 

exposures that would be anticipated. There was no mention of widespread mosquito spraying 

that takes place in many areas.”

The Wyoming Draft EA does not account for the commenter’s remarks due to the fact that there 

is no widespread mosquito abatement in the State of Wyoming. APHIS follows program 

guidelines and treatment strategies listed in the EIS and only treat an area once per year. 

Treatments rarely occur in the same locations year to year.

Comment 86

APHIS received the following comment, “as cattle are grazing these pesticides will be washed 

off their bodies or excreted through waste and contaminate surrounding land and water bodies.”

The labels for Dimilin 2L and Carbaryl 2% bait specify that there is no grazing restrictions. Any 

pesticide residues that may be present on forage in treated areas after treatment is typically 

metabolized and excreted as metabolites that have lower toxicity than the parent compound. In 

addition the low application rates employed by APHIS relative to the current maximum labelled 

rates for each Program insecticide would result in very low residues in livestock waste.

Comment 87

APHIS received the following comment, “A substantial acreage of rangeland is adjacent to lands 

used for plant agriculture, and the EAs state that they also aim to protect these agricultural lands. 

These areas generally have a high potential for crossover contamination through drift or runoff of 

pesticides. Large quantities of pesticides, including insecticides and fungicides that may be 

synergistic with the insecticides included in the EAs, may be used on these lands. In addition, 
63

herbicide use on crops already significantly impacts insects by destroying habitat and food 

sources in agricultural lands”.

The grasshopper program is a rangeland program and only rangeland is treated. Treatments on 

rangeland that is adjacent to agriculture lands also provide some protection from grasshoppers 

moving into crops. APHIS strictly adheres to pesticide labels which clearly state where their use 

is allowed or prohibited. 

Comment 88

APHIS received the following comment, “None of these issues were disclosed or analyzed in the 

Draft EIS and add to the already large cumulative exposures from pesticides used in 1) the boll 

weevil eradication program, 2) fruit fly cooperative eradication program, 3) the gypsy moth 

cooperative eradication program, and 4) invasive plant control”.

The commenter refers to the Draft EIS. The EIS has been finalized and the ROD has been 

signed. The final EIS does address the cumulative exposures from other APHIS programs on a 

programmatic level. The documents in question are the Draft EA’s. The first three programs 

mentioned by the commenter are not relevant to the Rangeland Grasshopper and Mormon 

Cricket Suppression Program in Wyoming. APHIS follows program guidelines and treatment 

strategies listed in the EIS and only treat an area once per year. Treatments rarely occur in the 

same locations. All grasshopper treatments are coordinated with the land managers and other 

non-grasshopper programs are discussed if the land managers are concerned about an overlap

with other programs.

Comment 89

APHIS received the following comment, “These cumulative exposures cannot only adversely 

affect human and environmental health but can also negatively impact biological control 

programs that try to manage insect and weed pests with natural predators”.

APHIS follows program guidelines and treatment strategies listed in the EIS and only treat an 

area once per year. Treatments rarely occur in the same locations. All grasshopper treatments 

are coordinated with the land managers and other non-grasshopper programs are discussed if 

the land managers are concerned about an overlap with other programs. APHIS’s preferred 

treatment chemicals and strategies are the most ecologically sound for non-targets such as 

biological control.

Comment 90

APHIS received the following comment, “How these pesticides act in conjunction with one 

another to additively or synergistically increase toxicity is not discussed and no mitigation 

measures were proposed. Therefore, APHIS must fully analyze the impacts from cumulative 

exposures and identify ways in which risk can be mitigated or prohibited”.

The Grasshopper Program does not apply treatments more than once per year to any rangeland 

area. Cumulative exposures from pesticides applied by external parties are not anticipated in 

most cases due to coordination between APHIS, land managers and other cooperators, on 
64

rangeland that may be receive grasshopper or Mormon cricket treatments. The EA details many 

procedures APHIS employs to mitigate risk.

Comment 91

APHIS received the following comment, “The project is vague and ill-defined, it improperly 

precludes the disclosure of environmental effects because the information on the project and its 

impacts is incomplete”.

The proposed Grasshopper treatment program described in the EA could occur within a specific 

area, using a limited number of insecticides and application methods. The environmental 

consequences of suppressing or not suppressing grasshopper infestations are analyzed in the EA 

and other programmatic risk analysis documents.

Comment 92

APHIS received the following comment, “APHIS’s explanation of a “level of economic 

infestation,” which is the trigger for insecticide spraying, does not give the public any sense 

whatsoever of when that threshold is met. The definition is too vague and ill-defined to meet 

NEPA’s purposes and mandates. The agency could spray with minimal infestation levels if it 

saw fit whenever it decided to do so. There must be a more concrete definition that identifies 

specific thresholds that must be met for the agency to determine an economic level of infestation 

has been met”.

APHIS utilizes and provides links to extensive resources for determining when a grasshopper 

outbreak is exceeding IPM thresholds including, “a level of economic infestation”. The Purpose 

and Needs section of the EA and supporting documents adequately define the multiple factors 

that must be evaluated before APHIS decides a treatment is necessary.

The “economic infestation level” is a measurement of the economic losses caused by a 

particular population level of grasshoppers to the infested rangeland. This value is determined 

on a case-by-case basis with knowledge of many factors including, but not limited to, the 

following: economic use of available forage or crops; grasshopper species, age, and density 

present; rangeland productivity and composition; accessibility and cost of alternative forage; 

and weather patterns. In decision-making, the level of economic infestation is balanced against 

the cost of treating to determine an “economic threshold” below which there would not be an 

overall benefit for the treatment. Short-term economic benefits accrue during the years of 

treatments, but additional long-term benefit may accrue and be considered in deciding the total 

value gained by treatment. Additional losses to rangeland habitat and cultural and personal 

values (e.g., aesthetics and cultural resources), although a part of decision-making, are not part 

of the economic values in determining the necessity of treatment.

Comment 93

APHIS received the following comment, “The EA’s description of the preferred alternative that 

includes “reduced agent area treatments” (“RAATs”) is similarly vague and ill defined”.

RAATs has long been in use, is public knowledge, and one of APHIS’s preferred IPM strategies, 

supported by decades of research. Skipping swaths are the most common RAATs choice, leaving 
65

50% of the treated area untreated to maximize refugia for non-target arthropods while 

simultaneously inducing target Orthoptera mortality at desired levels. RAATs are also described 

in detail in the final EIS that is incorporated by reference in the EA.

Comment 94

APHIS received the following comment, “It is unclear whether RAATs will even be used and 

how they will be used in the site specific area”.

APHIS’ preferred method of treatment is to use RAATs as a means to reduce program costs and 

potential environmental effects. However the program could decide to apply insecticides at 

conventional rates and total area coverage if a damaging grasshopper infestation warrants that 

level of suppression. These instances are rare due to monitoring and other technical assistance 

provided by APHIS. An explanation of the uncertainties involved with predicting grasshopper 

populations before they emerge is provided in section I.C. About this Process.

Comment 95

APHIS received the following comment, “APHIS could use the pesticide at 95% of the labelled 

rate and still call the application a RAAT.”

RAAT’s is defined as Reduced Agent and/or Area Treatments. The current pesticide labels for 

use in the Program do not allow applications at 95% of the labeled rate to be called RAATs.

This information was also summarized in the final EIS. EPA has approved the RAAT verbiage 

for each pesticide label. The labels clearly state which rates are allowed to meet a RAAT rate. In 

the case of Dimilin 2L label, which clearly states the application rates for RAAT’s is 0.75 - 1 

ounce per acre. “Use on rangeland only, in a RAAT’s application on early instars. A RAAT’s 

application is an IPM strategy that takes advantage of grasshopper movement and conservation 

biological control to allow Dimilin 2L to be applied on rangeland on a reduced treated area and 

at reduced rates, while sustaining acceptable control.”

The applicator can only use the RAAT’s rate of .75 or 1 ounce per acre. The label rate, if not 

using RAAT’s is 2 ounces/acre. The RAAT’s rate would be 50% of the label rate not 95% of 

labeled rate. 

In the case of using Carbaryl 5% bait the label rate is 20-40 lbs. per acre. APHIS uses the 

RAAT’s rate of 10lbs/acre. In the case of Carbaryl 2% bait, the label clearly states for ground 

applications 25 pounds/acre. It clearly states for U.S. Federal Government and State affiliated

Grasshopper/Mormon Cricket Suppression Programs using aerial applications the rate of 

application is 10 pounds/acre. So clearly the RAAT’s applications are 50% or less than the 

labeled rates.

In the case of a full coverage treatment, the total acreage is treated. In the case of reduced area 

portion of RAAT’s the treatment area would be 50% less than a full coverage treatment. The 

reduced area is achieved through alternating the treated and untreated swath widths. The 

RAAT’s application rates are described in detail in the Draft EA’s and depending on the 

pesticide used in a treatment, the label will also specify or clarify what the RAAT’s rate. The 

reduced area is achieved by skipping a treated swath. For example, if the swath width of the 
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treatment equipment is 40 feet, then the treated swath would be 40 feet. Then the adjacent swath 

would be skipped or untreated. The next treated swath would then be applied. So across the

treatment block would be treated and untreated swaths. Thus the reduced area of actual treated 

ground, instead of a conventional broadcast treatment.

The RAAT procedures used by the program are flexible to allow for a reduction of pesticide use. 

Typically the RAAT procedures will result in half the amount of pesticide being applied to a 

treatment block than conventional rates and total coverage. Program managers may reduce the 

rate at which the pesticide is sprayed from the aircraft or increase the distance between swaths 

that are sprayed based on factors specific to grasshopper populations being suppressed. It 

should be noted that APHIS average RAAT rates are lower than the labeled RAAT rates further 

reducing pesticide loading into the environment.

Comment 96

APHIS received the following comment, “The agency must give the public a more precise 

definition of when the threshold for spraying has been met (i.e. number of grasshoppers or 

crickets/acre and a full description of the economic interests at stake).”

APHIS utilizes and provides links to extensive resources for determining when a grasshopper 

outbreak is exceeding economic thresholds including, “a level of economic infestation”. The 

Purpose and Needs section of the EA and supporting documents adequately define the multiple 

factors that must be evaluated before APHIS decides a treatment is necessary. Establishing a 

treatment threshold based on the number of grasshoppers ignores a variety of factors that must 

be considered by program managers before treatments. Some examples include how voracious 

the individual species are that compose a grasshopper infestation and the hardiness of 

rangeland vegetation within a proposed treatment block. These factors are also discussed in the 

recently published final EIS and are incorporated by reference in the final EA.

Comment 97

APHIS received the following comment, “APHIS must also convey what metrics will be used to 

determine the area that will be sprayed in any given outbreak”.

The size and exact configuration of a treatment block cannot be forecast prior to the emergence 

of the grasshoppers, requests from land managers and other cooperators, and other 

environmental considerations such as buffers from water and sensitive species. The program 

procedures and mitigation measures are adequately described in the EA and supporting 

documents.

APHIS is unable to predict exactly what areas will be treated before conducting surveys and 

completing the EA. For ground applications, the terrain is key to be able to treat safely. If the 

terrain is too rough to safely drive a UTV, then the area is not treated even though other factors 

warrant a treatment. There are many variables taken into account before an area is treated.

Another factor that must be considered is the movement of populations. If for any number of 

reasons, a treatment can be delayed there is a risk that, depending on species, the boundaries 

will have to be readjusted to account for the movement of populations.
67

For example, it is documented that Melanoplus sanguinipes, the Migratory Grasshopper can 

swarm and fly up to 5-10 miles normally. The longest migrations recorded in 1938 were made by 

swarms that traveled from northeastern South Dakota to the southwestern corner of 

Saskatchewan, a distance of 575 miles (Pfadt, 1994). This is why it is critical to have a rapid 

response to outbreaks. Population dynamics of grasshoppers and Mormon crickets are fluid and 

responses have to be adaptable to the most current assessments to ensure successful suppression 

treatments while minimizing environmental impacts.

Comment 98

APHIS received the following comments, “The agency must accurately and comprehensively 

disclose and analyze the range of rare, sensitive, threatened, and endangered species, ecological 

areas, communities, Native American gathering grounds and sensitive receptors that could 

potentially be significantly affected by the proposed project” and “Without this baseline data the 

EA cannot disclose the environmental effects of the project”.

APHIS works in cooperation with Federal and State land managing agencies to protect sensitive 

resources managed on their lands. In Wyoming, Native American sacred places or special sites 

are only made available to APHIS when necessary. These places are not published or disclosed 

to the public as per conversations with BIA. They are addressed in general terms when published 

in the EA. Specific details are addressed during meetings with BIA. Sensitive or special BLM 

sites are not published or disclosed to the public as per conversations with BLM. These sites are 

also in general terms when published in the EA. Specific details are addressed during meetings 

with BLM. T&E species are analyzed during the USFWS Section 7 consultations. APHIS 

adheres to protective measures which have been agreed upon with USFWS and addressed in the 

letters of concurrence. See USFWS concurrence letter in Appendix 2.

PHIS adequately summarized available data for current baseline conditions in the draft EA. This 

includes cultural resources as well as the potential for any overlap of federally listed species 

with the proposed areas of treatment. 

Comment 99

APHIS received the following comment, “APHIS’s description of the environmental effects of 

the pesticides at issue failed to properly capture many of their environmental effects”.

APHIS prepared and published separate Final Human Health and Ecological Risk Assessments 

for all the pesticides used by the Grasshopper Programs (November 2019). These documents and 

the associated final EIS are incorporated by reference.

Comment 100

APHIS received the following comment, “Long-term exposure to carbaryl is associated with 

decreased egg production and fertility in birds”.

APHIS would make a single application per year to a treatment area, and could apply 

insecticide at an APHIS rate conventionally used for grasshopper suppression treatments, or 

more typically as reduced agent area treatments (RAATs). Carbaryl has a reported half-life on 

vegetation of three to ten days, therefore, long-term exposure to birds is not anticipated.
68

The study cited by the commenter noted. Carbaryl is practically nontoxic to birds on both an 

acute oral exposure (LD50 >2,000 mg/kg) and subacute dietary exposure basis (LC50 >5,000 

mg/kg of diet). In addition, no chronic effects were observed at a dietary exposure of 300 mg/kg 

of diet.

Comment 101

APHIS received the following comment, “Carbaryl is considered moderately toxic to mammals 

with decreased pup survival being the most sensitive effect”.

APHIS would make a single application per year to a treatment area, and could apply 

insecticide at an APHIS rate conventionally used for grasshopper suppression treatments, or 

more typically as reduced agent area treatments (RAATs). Carbaryl has a reported half-life on 

vegetation of three to ten days, therefore the chronic exposure to mammals that resulted in 

decreased pup survival is not anticipated.

Comment 102

APHIS received the following comment, “EPA has designated carbaryl as “highly toxic” to bees 

on a short-term exposure basis and ranged from moderately to highly toxic to other insects, mites 

and spiders”.

Although the Grasshopper Program has used the liquid formulation of carbaryl in the past, 

nearly all carbaryl applications this year and for the foreseeable future are likely to be a bait. 

The potential exposures of bees and other pollinators to carbaryl bait are minimal. The risks of 

carbaryl to bees and other non-target organisms are summarized in the human health and 

ecological risk assessment that was prepared to support the final EIS. This analysis is 

incorporated by reference into the final EA.

Comment 103

APHIS received the following comment, “Carbaryl is considered “highly toxic” to certain 

species of fish when exposed to short-term bursts and can reduce the number of eggs spawned 

when fish are exposed to lower levels over a longer period of time”.

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and Final 

Human Health and Ecological Risk Assessment for Carbaryl Rangeland Grasshopper and 

Mormon Cricket Suppression Applications are published. Comparison of the distribution of 

acute, sublethal and chronic effects data for fish to the residues estimated using ground and 

aerial ultra-low volume spray and bait applications show that the range of residues do not 

overlap with acute toxicity values, suggesting there is no acute risk to fish species. APHIS

determined there is some overlap with chronic and sublethal effect values and estimated 

residues. However, carbaryl half-lives in water are typically short and with the proposed one 

time application chronic exposure and risk to fish is not anticipated. Effects from consumption of 

contaminated prey are also not expected to be a significant pathway of exposure, based on the 

low residues and low bioconcentration factor values reported for carbaryl.
69

APHIS program guidelines describe buffers to bodies of water, streams and rivers are 

addressed in Appendix 1 of Draft EA WY-20-01 and the USFWS Section 7 consultations and 

USFWS letters of concurrence (Appendix 2). All reduce the exposure to fish species.

Comment 104

APHIS received the following comments, “Carbaryl has been designated “very highly toxic” to 

aquatic invertebrates on an acute exposure basis by the EPA and mesocosm studies that analyze 

how the pesticide affects aquatic community structure have found significant negative effects at 

low levels”.

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and Final 

Human Health and Ecological Risk Assessment for Carbaryl Rangeland Grasshopper and 

Mormon Cricket Suppression Applications are published. The risk assessment summarizes the 

available laboratory and field effects data for aquatic invertebrates and carbaryl. The risk 

assessment also summarized the potential exposure and risk to aquatic invertebrates. The EIS 

and carbaryl risk assessment are incorporated by reference into the EAs.

Comment 105

APHIS received the following comment, “The EPA identified potential interactions between 

carbaryl and the androgen pathway in fish, indicating that carbaryl is an endocrine disruptor in 

male aquatic vertebrates”.

Carbaryl half-lives in water are typically short and with the proposed one time application 

chronic exposure and endocrine disruption risk to fish is not anticipated. Effects from 

consumption of contaminated prey are also not expected to be a significant pathway of exposure, 

based on the low residues and low bioconcentration factor values reported for carbaryl. Chronic 

risk is also a conservative estimate because chronic toxicity data is based on long-term 

exposures that what would not be expected to occur from a single application, based on the 

environmental fate of carbaryl in aquatic environments. The final EIS and human health and

ecological risk assessment for carbaryl provides additional information regarding the 

effects of carbaryl to fish. APHIS program guidelines describe buffers to bodies of water, 

streams and rivers are addressed in Appendix 1 of Draft EA WY-20-01 and the USFWS Section 7 

consultations and USFWS letters of concurrence (Appendix 2). All reduce the exposure to fish 

species.

Comment 106

APHIS received the following comment, “On March 12, 2020, the EPA released a draft 

biological opinion finding that carbaryl is likely to adversely affect 1542 out of 1745, or 86% 

percent of all listed species in the U.S. and 713 out of 776 designated critical species’ habitats 

across the U.S.”.

The Endangered Species Act section 7 pesticide consultation process between the U.S. Fish and 

Wildlife Service and the National Marine Fisheries Service (the Services, collectively) and the 

EPA specifically concerns FIFRA pesticide registration and reregistration in the United States, 

including all registered uses of a pesticide. The state-level Biological Assessments for APHIS 
70

invasive species programs are separate from any consultations conducted in association with 

pesticide registration and reregistration process.

The Agricultural Improvement Act of 2018 (Farm Bill) created a partnership between USDA, 

EPA, the Services, and the Council on Environmental Quality to improve the consultation 

process for pesticide registration and reregistration. USDA is committed to working to ensure 

consultations are conducted in a timely, transparent manner and based on the best available 

science. The Revised Method for National Level Listed Species Biological Evaluations of 

Conventional Pesticides provides a directionally improved path to ensuring that pesticides can 

continue to be used safely for agricultural production with minimal impacts to threatened and 

endangered species.

APHIS provided information about use of carbaryl to EPA for the FIFRA consultation for 

carbaryl. The Grasshopper Program use of carbaryl has in the past comprised substantially less 

than 1% of the percent crop treated (PCT) for rangeland use of carbaryl. This is the case for the 

reasonably foreseeable future. For rangeland, in the EPA BE, the Grasshopper Program’s very 

low usage was rounded up to <1% PCT, which gives an overestimate of rangeland acres treated 

and thus endangered species risk. APHIS use of carbaryl is even smaller compared to all uses of 

carbaryl nationwide. Further, the Grasshopper Program consults directly with the Services to 

ensure program activities do not adversely affect protected species or their critical habitat.

Comment 107

APHIS received the following comment, “EPA found many Wyoming species were likely to be 

adversely affected. This is a chemical far too toxic for APHIS to consider using across wide 

swaths of land in Wyoming.”

Carbaryl is presently approved by the EPA and registered in Wyoming. It should be noted that 

the current labeled uses for carbaryl grasshopper treatments are at much higher rates and can 

be applied with more frequency than what APHIS is proposing for use in Wyoming. In addition 

carbaryl use by the Program is minor compared to the preferred alternative diflubenzuron.

APHIS has evaluated the risk of carbaryl use in the Program and in general the conclusions are 

consistent with other risk assessments demonstrating low risk when adhering to label 

requirements. Additional mitigation measures used by APHIS further reduces the risk to human 

health and the environment.

APHIS submitted a programmatic biological assessment to the USFWS in 2015. APHIS is 

currently working with the USFWS to update and complete the biological assessment and 

receive concurrence. The intent of the programmatic biological assessment is to provide 

consistent mitigation measures for listed species that may co-occur with Program treatments.

Consultation with the USFWS is still being completed at the local level prior to any treatments.

No APHIS treatments are made in States without prior concurrence from the USFWS regarding 

federally-listed species. This information is also summarized in the final EIS.

APHIS consulted with the USFWS on federally-listed species that may occur within the county or 

areas where grasshopper and Mormon cricket treatments may be required. APHIS works 

closely with the USFWS to determine the application of protection measures and where those 
71

measures should be applied prior to any treatments. APHIS also evaluated the potential direct 

and indirect impacts to non-target species which is summarized in the final human health and 

ecological risk assessments for each insecticide.

Comment 108

APHIS received the following comment, “The European Union banned carbaryl in 2007 due to, 

among other things, “...a high long-term risk for insectivorous birds and a high acute risk to 

herbivorous mammals, a high acute and long-term risk to aquatic organisms and a high risk for 

beneficial arthropods”.

APHIS summarizes the risk of carbaryl to non-target organisms in final human health and 

ecological risk assessment that was part of the recently published final EIS. Available effects 

data and the exposures that would be expected from proposed use in the grasshopper and 

Mormon cricket program are reduced based on mitigation measures (ex. RAATS, aquatic 

buffers) application methods and formulation types which further reduce risk.

Comment 109

APHIS received the following comments, “Carbaryl is classified as “likely to be carcinogenic to 

humans” based on treatment-related hemangiosarcoma development in mice”.

The levels of carbaryl that caused the above-mentioned effects to mice are above exposure 

concentrations that would be expected to occur for the public as well as workers and applicators 

in the APHIS grasshopper and Mormon cricket suppression program. The risk to human health 

from carbaryl use, including the proposed APHIS use, have been evaluated by APHIS and are 

discussed in the final human health and ecological risk assessment for carbaryl. It should be 

noted that other agencies have evaluated the risk to carbaryl at much higher application rates 

than those used in the grasshopper and Mormon cricket program.

Comment 110

APHIS received the following comments, “EPA has determined that humans can be exposed to 

more than 4 times the amount of carbaryl known to cause neurotoxicity from some legal uses of 

the pesticide. EPA also found that the current labelled uses of carbaryl may result in neurotoxic 

harms to mixers, loaders and applicators” and “use of this dangerous old pesticide must be 

discontinued and should not be considered for use in grasshopper and Mormon cricket 

eradication in Wyoming”. 

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and Final 

Human Health and Ecological Risk Assessment for Carbaryl Rangeland Grasshopper and 

Mormon Cricket Suppression Applications are published. APHIS evaluated the potential human 

health risks from the proposed use of carbaryl ULV sprays and carbaryl bait applications and 

determined that the risks to human health are low. The lack of risk to human health is based on 

the low probability of human exposure and the favorable environmental fate and effects data.

APHIS treatments are conducted in rural rangeland areas where agriculture is a primary 

economic factor. Rural rangeland areas consist of widely scattered, single dwellings in ranching 

communities with low population density. Risk to the general public from carbaryl ground or 
72

aerial applications is also expected to be minimal due to the low-population areas proposed for 

treatment, adherence to label requirements, and additional Program measures designed to 

reduce exposure to the public. APHIS is not obligated to analyze the risk posed by all legal uses 

of carbaryl, but rather the Grasshopper Program formulations and application rates.

The proposed use of carbaryl as a ULV spray, or a bait, and adherence to label requirements 

substantially reduces the potential for exposure to humans. APHIS does not expect adverse 

health risks to workers because of the low potential for exposure to carbaryl when applied 

according to label directions and use of personal protective equipment. APHIS quantified the 

potential risks associated with accidental exposure of carbaryl for workers during mixing, 

loading, and application. The quantitative risk evaluation results indicate no concerns for 

adverse health risk for Program workers from carbaryl applications in accordance with 

program standard operating procedures for safety.

As stated in the EA, the application of an insecticide within all or part of the outbreak area is the 

response available to APHIS to rapidly suppress or reduce, but not eradicate, grasshopper 

populations and effectively protect rangeland. At no time does APHIS ever strive to eradicate 

grasshoppers. 

Comment 111

APHIS received the following comment, “EPA has found that all use scenarios 

of chlorantraniliprole can result in direct or indirect effects to all listed species”.

The EPA risk assessment is a screening level ecological risk assessment that evaluated risk 

under a variety of application rates with most being well above use rates proposed in the APHIS 

Grasshopper Program. APHIS prepared a final human health and ecological risk assessment 

that assesses the risk of APHIS Program treatments. The state-level Biological Assessments for 

APHIS invasive species programs are separate from any consultations conducted in association 

with pesticide registration and reregistration process.

As previously stated, the Grasshopper Program will not be using chlorantraniliprole in 

Wyoming during 2020. Therefore any chlorantraniliprole exposure scenarios which the 

commenter is concerned about are not relevant at this time.

Comment 112

APHIS received the following comment, “EPA has found that all use scenarios 

of chlorantraniliprole can result in direct or indirect effects to all listed species. 

Chlorantraniliprole is considered “very highly toxic” to freshwater invertebrates and EPA found 

that many uses of it can result in acute and chronic harms to aquatic invertebrates. This was the 

case for both aerial and ground spray applications. Sublethal doses can impair locomotion in 

bees more than seven days post exposure. A 2013 European Food Safety Authority analysis 

of chlorantraniliprople found that the use of the pesticide poses a high risk to soil macroorganisms, aquatic invertebrates and sediment dwelling organisms.” and “APHIS must 

consider chlorantraniliprole substantial environmental impacts, including population level 

effects”.
73

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and Final 

Human Health and Ecological Risk Assessment for Chlorantraniliprole Rangeland Grasshopper 

and Mormon Cricket Suppression Applications is published. The document summarizes 

available effects data and characterizes risk to human health and non-target organisms based on 

the use pattern proposed by the Program. Results from the risk assessment suggest low risk 

of chlorantraniliprole to non-target aquatic organisms and most terrestrial invertebrates.

As previously stated, the Grasshopper Program will not be using chlorantraniliprole in 

Wyoming during 2020. Therefore any chlorantraniliprole exposure scenarios which the 

commenter is concerned about are not relevant at this time.

Comment 113

APHIS received the following comments, “Diflubenzuron is considered “highly” to “very highly 

toxic” to aquatic invertebrates. In a 2018 analysis, EPA found that the registered, labeled uses of 

diflubenzuron may result in freshwater invertebrate exposure at up to 550 times the level known 

to cause harm. Diflubenzuron exposure to honeybees and other pollinators at the larval stage was 

estimated to be more than 500 times the level known to cause harm. Although arthropods are not 

a part of EPA’s ecological risk assessment, the European Food Safety Authority found that 

“Juvenile non-target arthropods were very sensitive to diflubenzuron. Very large in-field nospray buffer zones would be needed to protect non-target arthropods. There is no reason for 

APHIS to exclude consideration of impacts to arthropods in its analysis of this pesticide.” 

and “APHIS also acknowledges the pollinator impacts but attempts to diminish them without 

providing evidence on how or why they are not significant”.

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and Final 

Human Health and Ecological Risk Assessment for Diflubenzuron Rangeland Grasshopper and 

Mormon Cricket Suppression Applications are published. The EPA risk assessment evaluated 

risk to aquatic organisms and pollinators based on application rates, methods of application and 

use patterns that would result in greater exposure and risk to aquatic and terrestrial 

invertebrates. APHIS evaluated risks to these groups of non-target organisms based on methods 

of application consistent with Program applications and other mitigation measures for 

diflubenzuron. The exposure potential is reduced compared to label uses due to many factors.

This includes but is not limited to reduced application rates, one application per season, use of 

RAATs and buffers from aquatic habitats. APHIS relied on laboratory and field collected data 

regarding diflubenzuron effects to aquatic and terrestrial invertebrates to show that risk is low 

for most non-target invertebrates. 

Characterization of risk to aquatic species from Program-specific diflubenzuron applications 

was made by comparing the residue values in the exposure analysis from ground and aerial 

applications to the distribution of available acute and chronic fish toxicity data. Residue values 

were below the distribution of acute and chronic response data, suggesting that direct risk to 

aquatic species is not expected from diflubenzuron applications. More specifically, the 

distribution of aquatic invertebrate toxicity data is above the residues estimated from spray drift 

models for Grasshopper Program ground and aerial applications of diflubenzuron.
74

The Endangered Species Act section 7 pesticide consultation process between the U.S. Fish and 

Wildlife Service and the National Marine Fisheries Service (the Services, collectively) and the 

EPA specifically concerns FIFRA pesticide registration and reregistration in the United States, 

including all registered uses of a pesticide. The Grasshopper Program treatments employ 

methods and diflubenzuron application rates that result in substantially lower freshwater 

invertebrate exposures than the rate cited by the EPA and the commenter.

The EPA Preliminary Risk Assessment to Support Re-registration Review examines all legal uses 

of diflubenzuron, of which the Grasshopper Program constitutes a small fraction. APHIS is not 

obligated to examine all legal uses of the pesticide, but rather those contemplated by the 

program. The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS 

and Final Human Health and Ecological Risk Assessment for Diflubenzuron Rangeland 

Grasshopper and Mormon Cricket Suppression Applications are published. Characterization of 

risk to aquatic species from diflubenzuron applications was made by comparing the residue 

values in the exposure analysis from ground and aerial applications to the distribution of 

available acute and chronic fish toxicity data. Residue values were below the distribution of 

acute and chronic response data, suggesting that direct risk to aquatic species is not expected 

from diflubenzuron applications. More specifically, the distribution of aquatic invertebrate 

toxicity data is above the residues estimated from spray drift models for Grasshopper Program 

ground and aerial applications of diflubenzuron.

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and Final 

Human Health and Ecological Risk Assessment for Diflubenzuron Rangeland Grasshopper and 

Mormon Cricket Suppression Applications are published. The APHIS analysis noted 

Diflubenzuron has low toxicity and risk to some non-target terrestrial invertebrates, including 

pollinators such as honey bees.

Comment 114

APHIS received the following comment, “APHIS also acknowledges the pollinator impacts but 

attempts to diminish them without providing evidence on how or why they are not significant. 

It does not mention that Wyoming is home to an amazing abundance of native bees and 

pollinators, and improperly uses honeybees as a surrogate for pollinators, when native pollinators 

are far more sensitive due to the lack of hive buffering effects. This is not a pesticide that should 

be applied to broad swaths of land. It is highly toxic to far too many species of importance in 

Wyoming.”

Grasshopper IPM field studies have shown diflubenzuron to have a minimal impact on ants, 

spiders, predatory beetles, and scavenger beetles. There was no significant reduction in 

populations of these species from 7 to 76 days after treatment. Although ant populations 

exhibited declines of up to 50%, these reductions were temporary, and population recovery was 

described as immediate (Catangui et al., 1996). No significant reductions in flying non-target 

arthropods, including honey bees, were reported. Within one year of diflubenzuron applications 

in a rangeland environment, no significant reductions of bee predators, parasites, or pollinators 

were observed for any level of diflubenzuron treatment (Catangui et al., 1996).

Comment 115
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APHIS received the following comment, “Diflubenzuron is commonly fed to ranging cattle as a 

way to control flies. This pesticide is present in the excreted manure and urine of cattle where 

they range. Therefore, any decision on whether to use diflubenzuron in these areas must consider 

that listed or non-listed species can be exposed to other sources of the pesticide. It is that 

cumulative exposure that must be considered in this decision – and is compelled by the ESA and 

NEPA’s mandate that an action agency take into account the environmental baseline”.

APHIS recognizes that some diflubenzuron resides may be present in urine and feces from cattle 

that feed on forage immediately after diflubenzuron treatment; however this pathway of 

exposure is expected to be minor based on the proposed use pattern of diflubenzuron in the 

Program. Low application rates applied only once per season will reduce the amount of 

diflubenzuron present in manure and urine. In addition some metabolism of 

diflubenzuron occurs in animals, and there will be further environmental degradation once 

excreted. 

Comment 116

APHIS received the following comment, “Malathion is considered “very highly toxic” to all 

aquatic and terrestrial invertebrates, as well as aquatic vertebrates such as fish. In addition 

indirect effects to taxa should be considered.”

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and Final 

Human Health and Ecological Risk Assessment for Malathion Rangeland Grasshopper and 

Mormon Cricket Suppression Applications are published. The risk assessment summarizes 

available laboratory and field collected aquatic and terrestrial effects data for malathion and 

then estimated risk based on conservative estimates of exposure. APHIS recognizes in the risk 

assessment that malathion can be toxic to sensitive non-target species however the effects have 

to be considered in relation to the potential for exposure to estimate risk, as well as historical 

use in the Program which is negligible. 

Comment 117

APHIS received the following comment, “When exposed to malathion for longer periods of 

time, female birds displayed regressed ovaries, reduced number of hatched eggs and enlarged 

gizzards”.

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and Final 

Human Health and Ecological Risk Assessment for Malathion Rangeland Grasshopper and 

Mormon Cricket Suppression Applications are published.

Several reproductive and developmental studies have been conducted with birds. The lowest 

median lethal dose to chicken embryos (eggs) was 3.99 mg per egg for 4-day embryos 

(Greenberg and LaHam, 1969). The median lethal concentration for field applications of 

malathion to mallard duck eggs was found to be 4.7 lbs. a.i./acre (Hoffman and Eastin, 1981). 

This is approximately five times greater than the maximum rate for rangeland grasshopper 

(0.928 lbs. a.i./acre), 7.6 times greater than the maximum APHIS application rate 

(0.619 lbs. a.i./acre), and nearly 19 times greater than the average RAATs rate applied by 

APHIS.
76

No effect on reproductive capacity of chickens was found at dietary concentrations as high as 

500 ppm in feed (Lillie, 1973). Based on the results from chronic reproduction studies using the 

bobwhite quail and mallard duck, the NOEC values were 110 and 1,200 ppm, respectively. The 

most sensitive endpoint in the quail study was regressed ovaries and reduced egg hatch at the 

next highest test concentration (350 ppm). The effect endpoint in the mallard study was growth 

and egg viability at the 2,400 ppm level Lowest Observed Effect Concentration (LOEC).

APHIS expects that direct avian chronic effects would be minimal for most species. The 

preferred use of RAATs during application reduces these risks by reducing residues on treated 

food items and reducing the probability that they will only feed on contaminated food items. In 

addition, malathion degrades quickly in the environment and residues on food items are not 

expected to persist.

Comment 118

APHIS received the following comments, “Malathion degrades into maloxon, which has been 

shown to be at least 22 times more toxic than the parent molecule”.

Similar to other organophosphate pesticides, malathion inhibits the enzyme AChE in the central 

and/or peripheral nervous system. Malathion is metabolized to malaoxon, which is the 

active AChE inhibiting metabolite. AChE inhibition is through phosphorylation of the serine 

residue at the active site of the enzyme, and leads to accumulation of acetylcholine and 

ultimately neurotoxicity. Malaoxon goes through detoxification with subsequent metabolism. 

Absorption and distribution of malathion and malaoxon are rapid with extensive metabolism and 

no accumulation in tissues.

Carboxylesterase detoxifies malathion and malaoxon to polar and water-soluble compounds for 

excretion. A rat metabolism study showed 80 to 90% of malathion excretion in the urine in the 

first 24 hours of exposure. Mammals are less sensitive to the effects of malathion than insects 

due to greater carboxylesterase activity resulting in less accumulation of malaoxon.

Available aquatic toxicity data show that malaoxon is approximately 1.5 to 6 times more toxic to 

fish and 1.8 to 93 times more toxic to amphibians. FMC, in their 2019 public response to 

the Grasshopper Program EIS, reported that malaoxon is 0.80 to 2.58 times more toxic to fish 

than malathion based on data that were determined to meet their criteria for 

acceptability (FMC, 2014). The conversion of malathion to malaoxon in aquatic environments 

can range from approximately 1.8 to 10% (CDPR, 1993; Bavcon et al., 2005; USEPA, 2012).

While APHIS assumed that malaoxon is most likely more toxic to aquatic invertebrates than the 

parent; however, due to its low percentage of occurrence in aquatic systems and its rapid 

breakdown, malaoxon is not anticipated to pose a greater aquatic risk when compared to 

malathion.

Comment 119

APHIS received the following comment, “A 2017 EPA biological evaluation also found that the 

use of malathion is likely to adversely affect 1778 out of 1835 listed species in the U.S. and 784 
77

out of 794 critical species’ habitats across the U.S. These findings were based on methodology 

recommended by the National Academy of Sciences. EPA found many Wyoming species were 

likely to be adversely affected, such as the yellow billed cuckoo. The U.S. Fish and Wildlife 

Service later drafted a biological opinion finding that malathion is likely to jeopardize the 

continued existence of 1284 threatened and endangered species. This is an astounding number of 

jeopardy calls for a single pesticide, and makes it even more astounding that APHIS would 

continue to consider using it for grasshopper and cricket control.”

The Endangered Species Act section 7 pesticide consultation process between EPA and the 

Services specifically concerns FIFRA pesticide registration and reregistration in the United 

States, including all registered uses of the pesticide. The Grasshopper Program use of malathion 

comprised nearly none of the percent crop treated for rangeland in the past, and this remains 

APHIS’ expectation for the foreseeable future. Further, the Grasshopper Program consults 

directly with the Services to ensure program activities do not adversely affect protected species 

or their critical habitat.

Comment 120

APHIS received the following comment, “California’s Proposition 65 list of chemicals known to 

cause cancer and has been designated as having suggestive evidence of carcinogenicity by the 

EPA for instances of liver, oral palate mucosa and nasal respiratory epithelium tumor formation 

in mice.”

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and Final 

Human Health and Ecological Risk Assessment for Malathion Rangeland Grasshopper and 

Mormon Cricket Suppression Applications are published. 

Comment 121

APHIS received a comment that, “EPA has determined that humans can be exposed to more than 

6 times the amount of malathion known to cause neurotoxicity from some legal uses of the 

pesticide. EPA also found that the current labelled uses of malathion may result in neurotoxic 

harms to those exposed to pesticide drift from aerial applications at labelled rates”. The 

commenter also pointed out that occupational applicators, mixers and loaders can be exposed to 

malathion through inhalation and dermal absorption at levels above what the EPA considers safe 

– even when using required personal protective equipment.”

APHIS evaluated the risk to human health, including neurotoxicity data in its finale human 

health and ecological risk assessment. The risk assessment was prepared based on APHIS use 

patterns and Program mitigations that reduce risk to human health. APHIS is not obligated to 

ensure the EA and supporting documents analyze the risk posed by all legal uses of malathion, 

but rather the Grasshopper Program methods and application rates.

Malathion exposure to the general public is not expected from the program use based on label 

requirements and program standard operating procedures that prevent potential exposure. Only 

protected handlers may be in the area during application, and entry of the general public into 

the treated area is not allowed during the re-entry interval period. APHIS treatments are 

conducted on rural rangelands, where agriculture is a primary economic factor and widely 
78

scattered dwellings in low population density ranching communities are found. The program 

requires pilots avoiding flights over congested areas, water bodies, and other sensitive areas. 

Aerial applications are not allowed while school buses are operating in the treatment area; 

within 500 feet of schools or recreational facilities; when wind velocity exceeds 10 miles per 

hour (mph) (unless a lower wind speed is required under State law); when air turbulence could 

seriously affect the normal spray pattern; and/or temperature inversions could lead to off-site 

movement of spray. The Grasshopper Program also notifies residents within treatment areas, or 

their designated representatives, prior to application to reduce the potential for incidental 

exposure.

APHIS acknowledges workers in the program are the most likely human population segment to 

be exposed to malathion during grasshopper treatments. Occupational exposure to malathion 

may occur through inhalation and dermal contact during ground and aerial applications. Direct 

contact exposure from the application of a malathion ULV spray will be minimal with adherence 

to label requirements, the use of personal protective equipment (PPE), general safety hygiene 

practices, and restricted entry intervals into treated areas after application. EPA estimates of 

risk to workers is based on use patterns and rates that result in greater exposure to malathion 

than would occur in the APHIS program. APHIS evaluated the risk from program specific uses 

of malathion and demonstrated low risk to applicators. It should also be noted that historical 

malathion use in the Program is negligible further reducing the potential for any types of human 

health risk.

Comment 122

APHIS received the following comment, “APHIS touts EPA-approval as an indication that the 

pesticides that the agency proposes to use are safe. However, under our nation’s pesticide laws, 

EPA-approval is an indication that use of the pesticide won the agency’s cost-benefit analysis, 

and should not be misconstrued as a finding of safety.”

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS 

and human health and ecological risk assessments for pesticides used by the 

Grasshopper Program are published. APHIS does not assert the FIFRA registration of the 

pesticides by the EPA demonstrates that the Grasshopper Program uses are safe. Instead the 

extensive risk analysis published by APHIS considered whether the suppression of grasshopper 

population will have significant environmental impacts, in accordance with NEPA.

Comment 123

APHIS received the following comment, “APHIS does not discuss or account for how pesticides 

impact overall soil health or the health of any organisms that reside in soil.”

The EA provided links to APHIS’ Grasshopper Program webpage where the 2019 EIS and 

HHERA for pesticides used by the Grasshopper Program are published. The HHERA contain 

extensive analysis of pesticide effects on terrestrial vertebrates, many of which reside in soil.

Comment 124
79

APHIS received the following comment, “Impacts on soil health can impact listed and non-listed 

plants by impacting nutrient cycling, soil oxygenation and soil water retention, as well as listed 

and non-listed animals that rely on plants or soil organisms for their survival.”

The Grasshopper Program applies pesticides in accordance with current label restrictions 

and program operational procedures that are mitigations to minimize significant exposure of 

soil, water, and air to insecticides; grasshopper chemical treatments are not expected to persist 

or bioaccumulate in the environment. APHIS evaluated these effects in human health and 

ecological risk assessments that were prepared along with the final EIS for the grasshopper and 

Mormon cricket suppression program.

Comment 125

APHIS received the following comment, “Carbaryl was ranked as extremely toxic to earthworms 

in a lab test rating pesticide toxicity from relatively nontoxic, moderately toxic, very toxic, 

extremely toxic, and super toxic.”

The study was a comparison of the toxicology of 45 pesticide to determine the LC50. These 

studies exposed earthworms to varying concentrations of carbaryl to determine toxicological 

endpoints. Based on the extremely high doses, the impact to the survival of earthworms was not 

only unsurprising, but the object of the studies. APHIS would like to note this laboratory dosing 

procedure is not comparable to any exposure levels resulting from the use of carbaryl ultra-low 

volume sprays by the Grasshopper Program.

Comment 126

APHIS received the following comment, “A single application of carbaryl in a field study caused 

a 38% reduction in survival of total Lumbricidae, and a 78% reduction in total earthworms for at 

least 5 weeks.”

APHIS would like to note the “single application” involved applying carbaryl 6 times on a 

weekly interval to its assigned plots at the highest recommended dose (i.e. Sevin at 9.12 mg/m2), 

a rate that is greater than 16 times the Grasshopper ultra-low volume liquid rate (0.56 mg/m2). 

The Grasshopper program only makes one application per year, rather than six weekly 

treatments. Also, the field study found carbaryl significantly inhibited earthworm feeding activity 

for at least three weeks without leading to any earthworm death.

In addition, the 78% reduction in earthworm casts noted in the comment resulted from an 

application of a combination of clothianidin and bifenthrin pesticides.

Comment 127

APHIS received the following comment, “Carbaryl significantly impacted the survival or 

population abundance of E. fetida, E. andrei, Lumbricus terrestris, 

and Lumbricus rubellus, Aporrectodea caliginosa, and Allolobophora chlorotica.”

These studies exposed earthworms to varying concentrations of carbaryl to determine 

toxicological endpoints (NOEC, LC50). Based on the extremely high doses, the impact to the 

survival of earthworms was not only unsurprising, but the object of the studies. For example in 
80

Lima et al. 2011, ten adult worms with individual fresh weight between 300 and 600 mg, were 

exposed to different carbaryl concentrations (20, 40, 60, 80, 100 mg/kg). APHIS would like to 

clarify the Grasshopper Program applies carbaryl ultra-low volume spray at a rate of half a 

pound active ingredient per acre.

Comparison of the results of paper contact test with those obtained in soils clearly demonstrates 

that the contact test has no predictive values for the toxicity of an insecticide in soils, though it is 

important for the initial screening of the environmental chemicals. The differences between 

lowest and highest LC50 values of insecticides for M. posthuma and E. fetida in paper contact 

method were only 6.9 and 2.5-fold respectively while in soil they were over 38 and 26-fold. 

These data demonstrated that worms could tolerate higher concentrations in soil than on moist 

filter paper. This difference in the behavior of the insecticide may probably due to the rate of 

diffusion/uptake of insecticide from the medium into the body of the earthworm. It is well 

reported in the literature that insecticides are adsorbed on soil medium through strong binding 

by organic matter contents in soils (Davis, 1971, Van Gestel and Van Dis, 1988). Hence, the 

availability of insecticide for diffusion will be less from the soil than the impregnated filter 

paper. Contact filter paper test can be used as an initial screening technique to assess the 

relative toxicity of chemicals; however it fails to represent the situation in the soil ecosystem. 

Artificial soil test is more representative of the natural environment of earthworms and acute 

toxicity data on several insecticides can be used in the ecological risk assessment on soil 

ecosystems.

Comment 128

APHIS received the following comment, “In another study, carbaryl induced an avoidance 

response in E. fetida. Soil structure changes were observed between the control and carbaryl 

treated sites, with higher treatments of carbaryl causing significantly more lumps in the soil due 

to earthworm inactivity.”

The commenter cited a study where worms were rinsed in tap water and transferred to the flasks 

containing 2 ml solution per worm. The flasks were gently tilted every 5 min and the exposure 

was terminated after 30 min. The worms were removed, rinsed in cold tap water and transferred 

to Petri dishes (five worms in each) containing soil but no pesticide. The worms were inspected 

at intervals during 80 days or until all the worms were dead or had recovered. The structure of 

the soil in the Petri dishes was observed in order to get an idea about the ability to work the soil 

after pesticide treatment. APHIS would like to note this laboratory dosing procedure is not 

comparable to any exposure scenario resulting from the use of carbaryl ultra-low volume sprays 

by the Grasshopper Program.

Notably, E. foetida could tolerate high concentrations of carbaryl without dying, although low 

concentrations severely affected its ability to work the soil or to disappear from the soil surface. 

The researchers believe the solutions were equivalent to 64, 32, 16, 8 and 4 mg/kg of pesticide, 

and found that carbaryl did not kill E. foetida in concentrations up to 64 mg/kg, from the 800 

mg/l solution.

The avoidance test is a behavioral test with several advantages (simple, quick and cheap) but 

one drawback: this is not a measure of toxicity but rather a measure of repellence 
81

(Capowiez and Bérard, 2006), and thus is termed ‘measure of habitat modification’. As there is 

not always a direct relationship between avoidance and toxicity, an improvement of this test was 

recently proposed by Sanchez-Hernandez (2006).

APHIS would like to clarify the Grasshopper Program applies carbaryl ultra-low volume spray 

at a rate of half a pound active ingredient per acre. If a cubic foot of rangeland soil weighs 75 

pounds, 1 acre (43,560 ft.2) of soil two inches deep would weigh 544,500 pounds, or 246,981 

kilograms. The maximum rate used by the Grasshopper Program to apply carbaryl as an ultralow volume spray is half a pound (226796 mg) active ingredient per acre. Therefore, the 

maximum concentration of 0.92 mg carbaryl spray per kg of soil could result from program 

applications. However, this analysis assumes none of the foliar spray settled on vegetation, 

and all of the carbaryl is instantaneously absorbed into the top two inches of soil. In addition, 

this maximum concentration was less than the lowest concentration which the researchers 

determined has significant effects on the reduction of the P. excavatus hatching rate (1.51 mg 

carbaryl per kg of soil). 

Comment 129

APHIS received the following comment, “Carbaryl negatively affected the biomass 

of E. andrei, Perionyx excavates, total earthworms, and Lumbricus terrestris at a tenth of the 

recommended dose.”

The carbaryl concentrations used for each test species was chosen based on the LC50/EC50 

previously carried out and reported by Lima et al. (2011). This was also a toxicological endpoint 

study where the acute toxicity was determined by exposing the worms to a nominal concentration 

range of 20 to 100 mg/kg of technical grade carbaryl. The application rate was 850 grams per 

hectare of Sevin L85 which is equal to 1.12 pounds active ingredient carbaryl per acre, 

compared with Sevin XLR which is 44.1 % applied at half a pound active ingredient per acre by 

the Grasshopper Program.

This study was primarily designed to validate the production of casts by earthworms as a 

biomarker for behavioral effects. While the significant effects in earthworm weight observed at 

low concentrations of carbaryl are concerning, Grasshopper program applications of foliar 

sprays are unlikely to result in the subsurface soil becoming saturated at the concentrations 

created in the laboratory.

Comment 130

APHIS received the following comment, “A 60-99% reduction in earthworm biomass and 

density due to carbaryl treatment lasted 20 weeks. Burial of organic matter was also negatively 

affected. Casting activity of earthworms was reduced by 90%, and 71% and 81% after 3 and 5 

weeks, respectively.”

The researchers made two applications of carbaryl at a rate of 8 lbs. a.i./acre, 16 times greater 

than the maximum spray rate employed by the Grasshopper Program. The Grasshopper 

Program only makes one application per year. In addition, the foliar spray of ultra-low volume 

carbaryl over rangeland is unlikely to result in subsurface soil concentrations comparable to the 

direct turfgrass application made in this study.
82

Comment 131

APHIS received the following comment, “Carbaryl negatively affected growth in E. fetida, and 

the feeding rate of Diplocardia spp. Total cast production of L. terrestris was significantly 

impacted at one-tenth of the recommended field rate.”

The lowest test concentration that effected E. fetida resulted from saturation of the test media 

with 25 mg/kg of carbaryl. Another field study found a single application of carbaryl 

significantly inhibited earthworm (Diplocardia spp.) feeding activity for at least three 

weeks without leading to any earthworm death. APHIS would like to note the “single 

application” involved applying carbaryl 6 times on a weekly interval to its assigned plots at the 

highest recommended dose (i.e. Sevin at 9.12 mg/m2), a rate that is greater than 16 times the 

Grasshopper ultra-low volume liquid rate (0.5 lbs. a.i./acre). The Grasshopper program only 

makes one application per year, rather than six weekly treatments.

Comment 132

APHIS received the following comment, “Reproduction of E. fetida, and Perionyx excavatus

was negatively affected, with the hatching rate of P. excavatus reduced by 87% at sublethal 

concentrations lower than the recommended field rate. A total loss of burrowing was observed at 

4 and 8 mg/kg after 40 minutes and at 1 and 2 mg/kg after 80 minutes.”

The lowest test concentration that effected E. fetida resulted from saturation of the test media 

with 25 mg/kg of carbaryl. In another study the reduction of the P. excavatus hatching rate was 

observed at a concentration of 1.51 mg carbaryl per kg of soil.

APHIS would like to clarify the Grasshopper Program applies carbaryl ultra-low volume spray 

at a rate of half a pound active ingredient per acre. If a cubic foot of rangeland soil weighs 75 

pounds, 1 acre (43,560 ft.2) of soil two inches deep would weigh 544,500 pounds, or 246,981 

kilograms. The maximum rate used by the Grasshopper Program to apply carbaryl as an ultralow volume spray is half a pound (226796 mg) active ingredient per acre. Therefore, the 

maximum concentration of 0.92 mg carbaryl spray per kg of soil could result from program 

applications (0.92 mg/kg). However, this analysis assumes none of the foliar spray settled on 

vegetation, and the carbaryl instantly absorbed into the top two inches of soil, thus mirroring the 

laboratory conditions. In addition, this maximum concentration was less than the lowest 

concentration which the researchers determined has significant effects on the reduction of the 

P. excavatus hatching rate (1.51 mg/kg).

Comment 133

APHIS received the following comment, “Morphological abnormalities and histological changes 

in E. andrei and M. posthuma were observed at very low, sublethal doses ranging from 0.24-1.20 

mg/kg and 0.5-1.20 mg/kg, respectively.”

The cited study did not test E. andrei but rather E. fetida a closely related species. The sublethal 

doses were derived from anecdotal observations during filter paper tests where concentrations 

were measured in μg/cm2 not mg/kg. APHIS would also like to note the researcher’s skepticism 

about toxicity tests where the worms are dosed on saturate filter paper. They wrote: Comparison 
83

of the results of paper contact test with those obtained in soils clearly demonstrates that the 

contact test has no predictive values for the toxicity of an insecticide in soils, though it is 

important for the initial screening of the environmental chemicals. The differences between 

lowest and highest LC50 values of insecticides for M. posthuma and E. fetida in paper contact 

method were only 6.9 and 2.5-fold respectively while in soil they were over 38 and 26-fold. 

These data demonstrated that worms could tolerate higher concentrations in soil than on moist 

filter paper. This difference in the behavior of the insecticide may probably due to the rate of 

diffusion/uptake of insecticide from the medium into the body of the earthworm. It is well 

reported in the literature that insecticides are adsorbed on soil medium through strong binding 

by organic matter contents in soils (Davis, 1971, Van Gestel and Van Dis, 1988). Hence, the 

availability of insecticide for diffusion will be less from the soil than the impregnated filter 

paper. Contact filter paper test can be used as an initial screening technique to assess the 

relative toxicity of chemicals; however it fails to represent the situation in the soil ecosystem. 

Artificial soil test is more representative of natural environment of earthworms and acute 

toxicity data on several insecticides can be used in the ecological risk assessment on soil 

ecosystem.

Comment 134

APHIS received the following comment, “Carbaryl impacted multiple biochemical biomarkers in 

E. andrei, including Acetylcholinesterase (AChE), methoxyresorufin-O-deethylase (MROD), and 

NADH and NADPH red cytochrome reductase.”

This study exposed earthworms to carbaryl in artificial soil at concentrations of 12, 25 and 50 

mg/kg. The research showed that carbaryl inhibited biotransformation enzyme activities but did 

not induce oxidative stress. Since carbaryl is a cholinesterases inhibitor, changes detected in 

acetylcholinesterase activities were not surprising. The acetylcholinesterase activity reduction 

was not complete and the residual activity was stable whatever the dose or the exposure duration 

because of the presence in E. andrei of a non-inhibited, non-specific cholinesterases.

APHIS would like to note the lowest tested soil concentration of carbaryl that caused these 

effects (12 mg/kg) is approximately 12 times greater than the hypothetical concentrations that 

could result from Grasshopper Program treatments where none of the foliar ultra-low volume 

spray settles on vegetation, and the chemical is instantly and uniformly mixed into the top two 

inches of soil.

Comment 135

APHIS received the following comment, “AChE activity was inhibited in E. fetida in two 

studies, one of which resulted in muscular paralysis that directly impacted earthworm burrowing 

capabilities.”

In the first study, carbaryl stock solution was prepared in acetone and water to yield final 

concentrations of 1, 2, 4 and 8 parts per million. Five earthworms were individually exposed for 

5, 10, 20, 40 and 80 minute intervals in a 50ml beaker containing 2.0ml of various 

concentrations of test solution. The researchers asserted the test concentrations used in the study 

were close to expected residues in the soil without any evidence or analysis as proof. They also 

used higher concentrations to exert significant inhibition of AChE activity and loss of burrowing 

in earthworms for establishing a dose effect “correlationship”. These higher exposures occurred 
84

after the individual worms were rinsed in tap water, their borrowing rate was measured, they

were rinsed again, and then placed back into the solution. Needless to say this systematic dosing

in a pesticide solution does not match any exposure levels that could result from the application 

of ultra-low volume sprays.

While the significant reduction in the ability of worms to burrow in soil was clearly evident at 

the lowest test concentration (1 ppm) and the earliest period of exposure (5 min), all worms were 

alive and fully recovered to normal behavior (no tremors, efficient burrowing) 18 hrs.

post-exposure to 1 ppm carbaryl.

The second study cited by the commenter measured AChE responses in earthworms exposed to 

carbaryl on filter paper and in a soil media. APHIS has previously noted the difficultly 

extrapolating between filter paper toxicological tests to actual exposure scenarios relevant to the 

Grasshopper Program treatments. While the AChE inhibition reached significance after one day 

of exposure to 0.48 mg/kg carbaryl, the researchers did not conclude there was a reduction of 

burrowing capacity. Pure carbaryl was used as a liquid solution, while Zoril 5 was applied as a 

powder spread on the soil. Zoril 5 was thus more abundant on the superficial soil fraction, and 

was immediately in contact with the animals, whereas pure carbaryl penetrated into the soil and 

probably became bioavailable later. APHIS would also like to note the tested application rate of 

17.8 pounds per acre carbaryl 5% powder formulation (Zoril 5), that was estimated to result in a 

concentration of 4.29 mg/kg was nearly twice the maximum Grasshopper Program carbaryl bait 

rate and had no effect on earthworm AChE activity or the lysosomal membrane stability of 

E. andrei.

Comment 136

APHIS received the following comment, “In addition to earthworms, carbaryl negatively 

affected collembola population abundance and reproduction.”

The first and second studies cited by the commenter did not investigate carbaryl or collembola 

(Panda and Sahu, 2004, and Stepić, et al., 2013). The third paper cited used carbaryl as a toxic 

standard for comparison of the effects of other pesticides (Larson et al., 2012). The researchers 

applied carbaryl at a rate of 8.17 lbs. a.i./acre. Researchers conducting the fourth study cited by 

the commenters (Potter et al., 1990) made two applications of carbaryl at the same rate of 8.17 

lbs. a.i./acre, 16 times the maximum rate used by the Grasshopper Program in ultra-low volume 

sprays. The Grasshopper Program only makes one application per year. Therefore this study 

used 32 times the carbaryl rate as the program. In addition, the foliar spray of ultra-low volume 

carbaryl over rangeland is unlikely to result in subsurface soil concentrations comparable to the 

direct turfgrass application made in this study.

The next study cited by the commenters (Joy and Chakravorty, 1991) investigated carbaryl 

toxicity to collembola. Adult specimens of Cyphoderus sp. and Xenylla sp. and Lancetoppia sp. 

were exposed to soils saturated with solutions ranging from 0.5 to 10 ml/l. Although they noted 

the standard agricultural doses of carbaryl 50 WP was 6.25 ml/l, the researchers did not provide 

a sufficient description of their methods for APHIS to make a valuable comparison of the 

exposure rates of the collembola in the experiment to potential exposure levels resulting from 

Grasshopper Program treatments.
85

The commenters cited another study to suggest carbaryl effected collembola reproduction. Three 

nominal concentrations of carbaryl (1, 4 and 7 mg/kg) in soil chemical behavior and toxicity 

were investigated at different temperatures. After 15 days from soil spiking, it was observed that 

carbaryl concentration in soil decreased to 30% and 33% of the initial concentration at the 

temperature extremes of 8 °C and 28 °C, respectively, and 22.8% of the initial concentration 

under a 20 °C temperature regime. The collembola survival and reproduction were 

significantly affected at 4 and 7 mg/kg concentrations, approximately 4 and 7 times greater than 

hypothetical soil concentrations resulting from Grasshopper Program ultra-low volume sprays 

(see previous comments for estimations parameters).

Comment 137

APHIS received the following comments, “Carbaryl also negatively impacted Prostigmata mites, 

and Tiphia vernalis, a wasp that feeds on scarab beetle larvae in the soil.”

In the first study cited carbaryl applied at a rate of 8.18 lbs. a.i./acre, greater than 16 times the 

Grasshopper Program’s maximum rate, as a toxic standard for comparison of various pesticide 

control efficacy. The effects on oribatid and mesostigmatid mites was not surprising or 

comparable to exposure levels resulting from applications of carbaryl ultra-low volume sprays.

The commenters are mistaken, in that the research cited did not find effects 

on Tiphia vernalis (Helson et al., 1994).

Comment 138

APHIS received the following comment, “Carbaryl can be particularly toxic to ground-nesting 

bees, like Andrena erythronii, Bombus terrestris, and Bombus terricola.”

The commenters cited a toxicology study where carbaryl was applied topically to the thorax of 

the bees to investigate lethal doses and determine the concentration values in units of μg a.i./g 

body weight and of μg a.i./bee. This dosing method is not comparable to any exposure scenario 

resulting from the Grasshopper Program treatments using ultra-low volume sprays. APHIS 

would like to note that of the six insecticides tested, carbaryl had the second lowest relative 

toxicity, rather than as the commenter characterized being particularly toxic to ground-nesting 

bees. The researchers noted their study does not suggest an inherent, physiological relationship 

between size and pesticide susceptibility, and they further suggested that bumble bees may be at 

relatively little risk from carbaryl, contrary to the commenter’s suggestion of particular toxicity 

to Bombus terricola. The researcher’s elaborated carbaryl previously was not found to have 

significant effects on bumble bees, citing Hansen and Osgood (1984). 

The acute effects of carbaryl on B. terrestris were investigated for ingestion and topical contact 

in another cited study. The researchers found the calculated hazard ratio for oral exposures of 

carbaryl (309) was below the mean (1399) and the median (381) of the 14 pesticides tested and 

reported. Carbaryl was not found to be toxic through topical exposure at the “highest dose 

advised on the label.” The hazard ratio values permit only a comparative evaluation between the 

different active compounds tested.
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Comment 139

APHIS received the following comment, “Carbaryl caused 100% mortality 

in Nomia melanderi when exposed to field-rate pesticide residues 3 hours post-application, 97% 

mortality with 8 hours post-application, and 78% mortality 2 days post application. Carbaryl was 

more toxic than DDT.”

APHIS does not use DDT during Grasshopper Program treatments and does not agree that the 

relative toxicity to carbaryl is a concern. The study cited by the commenter did not test carbaryl 

toxicity on bees, but rather included data from earlier studies. The application rate of carbaryl 

emulated in the earlier studies was I.0 lbs. 80% wettable powder per acre, approximately twice 

the maximum ultra-low volume rate used by the Grasshopper Program. APHIS found the 

literature did not provide sufficient details for a reasonable comparison of the carbaryl 

application methods and rates for additional effects analysis.

Comment 140

APHIS received the following comment, “Bombus impatiens colony vitality (as measured by 

colony weight, worker weight) and the number of workers, honey pots, and brood chambers was 

reduced following carbaryl exposure.”

The researchers noted the confinement of the bee colonies within cages represent a worst case 

scenario in that the workers were caged on the sprayed plots for two or four weeks. Wholecolony consequences of a smaller proportion of the workers foraging on insecticidecontaminated weeds in an open system likely would be less severe. In addition, the researchers 

explained extent to which an insecticide is hazardous to pollinators is determined by its inherent 

toxicity as well as the formulation and manner in which it is applied (Stark et al. 1995). For 

example, pollen contamination, which can decimate honey bee colonies, may be exacerbated 

by wettable powder or microencapsulated formulations that have high affinity for binding to 

pollen (Johansen et al. 1983).

APHIS would also like to note the direct application of carbaryl to turfgrass at rates ten times 

greater (5.44 lbs. a.i./acre) than the maximum rate used by the Grasshopper Program (0.5 

lbs. a.i./acre) is not comparable to ultra-low volume foliar spray treatments.

Comment 141

APHIS received the following comment, “In a laboratory study, chlorantraniliprole negatively 

inhibited the enzymes acetylcholinesterase and glutathione-S-transferase in Eisenia fetida.”

As previously stated, the Grasshopper Program will not be using chlorantraniliprole in 

Wyoming during 2020. Therefore any chlorantraniliprole exposure scenarios which the 

commenter is concerned about are not relevant at this time.

Comment 142

APHIS received the following comment, “Chlorantraniliprole negatively affected Folsomia

candida (collembola) reproduction.”
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As previously stated, the Grasshopper Program will not be using chlorantraniliprole in 

Wyoming during 2020. Therefore, any chlorantraniliprole exposure scenarios which the 

commenter is concerned about are not relevant at this time.

Comment 143

APHIS received the following comment, “Microscopic examination in an avoidance test 

revealed that the collembola were paralyzed from the chlorantraniliprole treatment and couldn't 

migrate, clarifying an observed avoidance at 1 mg/kg, but no avoidance at any higher 

concentrations. The authors note that chlorantraniliprole may be more toxic to non-target 

arthropods closely related to insects than to other soil invertebrates.”

As previously stated, the Grasshopper Program will not be using chlorantraniliprole in 

Wyoming during 2020. Therefore, any chlorantraniliprole exposure scenarios which the 

commenter is concerned about are not relevant at this time.

Comment 144

APHIS received the following comment, “In the field, ground-nesting bumble bees (Bombus 

impatiens) treated with chlorantraniliprole consumed less pollen than control bees.”

As previously stated, the Grasshopper Program will not be using chlorantraniliprole in 

Wyoming during 2020. Therefore any chlorantraniliprole exposure scenarios which the 

commenter is concerned about are not relevant at this time.

Comment 145

APHIS received the following comment, “Staphylinidae (Coleoptera) population abundance was 

slightly but significantly suppressed.”

As previously stated, the Grasshopper Program will not be using chlorantraniliprole in 

Wyoming during 2020. Therefore any chlorantraniliprole exposure scenarios which the 

commenter is concerned about are not relevant at this time.

Comment 146

APHIS received the following comment, “After one application of diflubenzuron, myriapoda

populations were nearly eradicated (73% reduction), gamasina mites were reduced by 40%, 

and uropodina mites were reduced by 57%. Diflubenzuron treatment reduced the populations of 

oribatid mites, prostigmata mites, and soil arthropod larvae, mostly comprised of coleoptera 

and diptera, by nearly 15%.”

The cited research does not suggest Grasshopper Program applications of diflubenzuron will 

result in significant impacts to soil microfauna. The researchers applied diflubenzuron to plots 

and investigated the effects on Collembola, Insecta, Myriapoda, and 4 groups of mites for 6 

months. The observed taxa abundance fluctuated seasonally, but for a majority of taxa no 

significant differences were noticed between the control and exposed plots. The total number of 

microarthropods was insignificantly lower in exposed groups. While myriapods were the only 
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taxon that was close to extinction after a single exposure to diflubenzuron the pesticide was 

applied directly to the soil at a rate four times greater than the maximum conventional

application rate used by the program. The researchers noted their data proved that soil has some 

buffering capacity, and this fact should always be taken into consideration when estimating the 

risk for the environment.

Comment 147

APHIS received the following comment, “In a field study, collembola populations were 

negatively affected by diflubenzuron and did not recover for one and a half years. The 

earthworms, Dendrobaena rubidus and Lumbricus rubellus were reduced in plots treated with 

concentrations of diflubenzuron at half the recommended field rate. Gamasid and oribatid mite 

populations were additionally reduced, and oribatida were observed migrating into deeper soil 

layers to avoid the pesticide.”

The commenters have cited a study where the researchers applied two treatments of 

diflubenzuron wettable powder directly to the forest floor at a rate 37% higher than the 

maximum rate used by the Grasshopper Program. Contrary to the characterization of the 

research findings presented by the commenter, the mean population size of earthworms did not 

differ significantly during the potential effect phase between control and the 137% the 

Grasshopper Program rate treatment plot. The populations of the enchytraeid species 

E. buchholzi, E. minutus, E. norvegicus and M. clavata did not respond to this 137% treatment of 

diflubenzuron applied twice per growing season. While the number of oribatids decreased after 

the application of the insecticides in all experimental plots including the control, these 

differences were only significant in the plot were diflubenzuron was applied directly to the forest 

floor at a rate nearly 14 times greater than the maximum Grasshopper Program rate.

Where Brachychthoniid populations declined significantly in the diflubenzuron treated plots, the 

reductions were in part compensated by changes in numbers of the dominant genus Oppiella.

The researchers explained the half-life of diflubenzuron in soil is reported to range from 1 to 27 

days, which was borne out by their data. Therefore, residue accumulations in the organic layer 

is unlikely if diflubenzuron is only applied once per year.

The researchers acknowledged that there could be several potential reasons for differences in 

populations of soil invertebrates between the study plots. First, the plots could differ independent 

of any treatment. APHIS agrees this is a reasonable interpretation because of the small sample 

sizes during the pre-application, potential effect and early recovery data recording phases (I.e.

four plots including the control, five sample dates, two replicates, n=10). The testing of natural 

variation during the 9 month pre-application phase may not have been sufficient. They decided 

to interpret deviations as a response to a treatment, if numbers in the potential effect phase were 

different to those in the other phases in the same plot and to the control in the same phase.

Comment 148

APHIS received the following comment, “Diflubenzuron treatment resulted in a total loss in 

brood production of male Bombus terrestris, and 100% inhibition of egg hatching success and 

larval growth. Transovarial transport and accumulation of the pesticide in deposited eggs 

explained the total loss of reproduction. Abnormal cuticle formation, which can lead to 
89

mechanical weakness and death, was observed in dead larvae that worker bees were observed 

removing from treated nests.”

The commenters have cited a study where the B. terrestris was directly dosed with diflubenzuron 

to test acute toxicity. Adult worker bees were exposed via contact by topical application and 

orally via drinking sugar water and by eating pollen. For contact application, 50 μL of the 

aqueous concentration was topically applied to the dorsal thorax of each worker with a 

micropipette. The worker bumblebees were also provided diflubenzuron treated sugar-water for 

drinking for 11 weeks. Bumblebees can also be exposed orally to pollen sprayed until saturation 

with a diflubenzuron concentration. Both the sugar water and pollen were supplied for unlimited 

oral consumption.

While APHIS acknowledges the effects of acute diflubenzuron exposures on the egg hatching and 

larval stages of bumble bees is a concern, the direct dosing conducted by the researchers is not 

comparable to any exposure levels that could result from the Grasshopper Program 

diflubenzuron ultra-low volume spray treatments.

In addition, APHIS would like to note, no acute mortality was observed after topical application, 

nor after oral exposure to treated sugar-water or treated pollen. In all cases, the number of dead 

worker bees in the treated nests over a period of 11 weeks was not above that of the control 

groups using water (0–10%).

Comment 149

APHIS received the following comment, “Multiple studies have observed AChE inhibition in 

earthworms when malathion was applied. Malathion effected the sperm count and viability and 

testicular histology of male E. fetida at sublethal concentrations, potentially impairing population 

abundance.”

APHIS agrees with the commenter that the main acute poisonous effect of malathion is the 

inhibition of the enzyme acetylcholinesterase, and acute poisoning such as was carried out by 

the researchers with direct exposures to high concentrations of the pesticide could occur in many 

types of organisms including earthworms. The direct dosing of earthworms to validate their use 

as toxicological test organisms does not mimic any exposure scenario resulting from the 

Grasshopper Program use of ultra-low volume sprays of malathion.

To further illustrate the disparity between exposures resulting from laboratory toxicity tests and 

grasshopper suppression treatments APHIS would like to note the lowest tested concentration

was 80 mg/kg of soil. The Grasshopper Program applies malathion ultra-low volume spray at a 

rate of 0.62 pounds active ingredient per acre. If a cubic foot of rangeland soil weighs 75 

pounds, 1 acre (43,560 ft.2) of soil two inches deep would weigh 544,500 pounds, or 246,981 

kilograms. The maximum rate used by the Grasshopper Program to apply malathion as an ultralow volume spray is 0.62 pounds (281227 mg) active ingredient per acre. Therefore, the 

maximum concentration of 1.14 mg malathion spray per kg of soil could result from program 

applications. However, this analysis assumes none of the foliar spray settled on vegetation, and 

the malathion instantly absorbed into the top two inches of soil. This hypothetical soil 
90

concentration resulting from ultra-low volume sprays should not be compared in a risk analysis 

with the 80 mg/kg tested for sub-lethal effects in the laboratory.

Comment 150

APHIS received the following comment, “In addition to AChE, the biochemical biomarkers 

glutathione-S-transferase, and catalase were also inhibited by malathion in studies 

with Eisenia andrei. Malathion has also been observed to negatively affect the reproduction 

of E. andrei.”

The commenters have cited research that confirms malathion inhibits AChE in earthworms. 

While APHIS does not dispute this effect, the agency doubts such effects could result in 

significant impacts. Notably the researchers found the inhibition period suggests lengthening of 

retreatment intervals to 45 days is the appropriate conclusion from the study. APHIS only makes 

one suppression treatment per year to grasshopper infested rangeland.

Comment 151

APHIS received the following comment, “Malathion had a severe effect on AChE activity 

in Drawida willsi. Growth, casting activity, and respiration of D. willsi was negatively affected 

by malathion treatment and did not recover for 75, 60, and 30 days, respectively.”

The commenters have cited research that confirms malathion inhibits AChE in earthworms. 

While APHIS does not dispute this effect, the agency doubts these biomarker effects could result 

in significant impacts.

The study cited by the commenters described malathion’s recommended agricultural dose as 2.7 

to 4.0 kg a.i./ha and calculated the equivalent 1.5 to 2.22 mg a.i./kg soil, which APHIS would 

like to note are comparable to the concentration estimation provided above. However the toxicity 

results for a single dose of malathion were reported for a concentration of 2.2 mg a.i./kg which 

is equivalent to double the dose of 4.0 kg a.i./acre, nearly six times the application rate used by 

the Grasshopper Program. 

Comment 152

APHIS received the following comment, “In addition to AChE, the biochemical biomarkers 

glutathione-S-transferase, and catalase were also inhibited by malathion in studies 

with E. andrei. Malathion has also been observed to negatively affect the reproduction 

of E. andrei.”

The commenters have cited two toxicology studies where earthworms were placed in test tubes 

lined with malathion saturated filter paper to determine acute effect concentrations, extrapolated 

from the biomarker, AChE reduction. The dosing methods and units of ug a.i./cm2 are not 

comparable to any exposure levels that could result from the application of malathion ultra-low 

sprays by the Grasshopper Program. The study cited by the commenter did not make any 

conclusions regarding malathion affecting reproduction of E. andrei.

Comment 153
91

APHIS received the following comment, “In a lab test rating the toxicity of 45 pesticides 

to E. fetida, malathion was ranked moderately toxic with an LC50 of 114.4 ug/cm.”

The study cited by the commenter was a comparison of the toxicology of 45 pesticide to 

determine the LC50. These studies exposed earthworms to varying concentrations of carbaryl to 

determine toxicological endpoints. Based on the extremely high doses, the impact to the survival 

of earthworms was not only unsurprising, but the object of the studies. APHIS would like to note 

this laboratory dosing procedure is not comparable to any exposure scenario resulting from the 

use of malathion ultra-low volume sprays by the Grasshopper Program.

Comment 154

APHIS received the following comment, “Malathion caused a 40% decrease in survival of the 

ground-nesting bee, Nomia melanderi.”

The study cited by the commenter did not test malathion toxicity on bees, but rather included 

data from earlier studies. The application rate of malathion emulated in the earlier studies was 

I.0 lb. of emulsifiable concentrate per acre, significantly greater than the maximum ultra-low 

volume rate used by the Grasshopper Program. APHIS found the literature did not provide 

sufficient details for a reasonable comparison of the malathion application methods and rates 

for additional effects analysis.

Comment 155

APHIS received the following comment, “The EAs an agency action subject to this consultation 

requirement, must be prepared “concurrently with and integrated with environmental impact 

analyses . . . required by . . . the Endangered Species Act of 1973.”

The commenter has again confused the EA prepared by APHIS for the Grasshopper Program in 

Wyoming with other environmental risk analysis documents. See comment/response 156 below.

Comment 156

APHIS received the following comment, “In order to properly provide information to the public 

for commenting on the EIS and the EAs, the section 7 process should be completed prior to the 

completion of NEPA. APHIS must ensure that consultation addresses all species and critical 

habitat that could be directly and indirectly affected by the proposed project.” The commenter

also states that APHIS has not complied with its responsibilities under Section 7 of the ESA.

As stated in the final EIS, APHIS has completed programmatic consultation with the National

Marine Fisheries Service (NMFS). APHIS has reinitiated programmatic consultation with 

NMFS to include chlorantraniliprole. In the interim APHIS will consult with NMFS at the State 

level if there is a proposal to apply chlorantraniliprole. The NMFS consultation does not apply 

to species in Wyoming since there are no federally listed species under NMFS jurisdiction 

however the information was provided in response to comments regarding the final EIS. APHIS

submitted a programmatic biological assessment to the USFWS in 2015. APHIS is currently 

working with the USFWS to update and complete the biological assessment and receive 

concurrence. The intent of the programmatic biological assessment is to provide consistent 

mitigation measures for listed species that may co-occur with Program treatments. In the 
92

meantime consultations with the USFWS are still being completed at the local level prior to any 

treatments. No APHIS treatments are made in States without prior concurrence from the USFWS 

or NMFS regarding federally-listed species. This information is also summarized in the final 

EIS.

Local USFWS Section 7 consultations were entered into prior to the DRAFT EA. APHIS 

consulted with the USFWS on federally-listed species that may occur within the county or areas 

where grasshopper and Mormon cricket treatments may be required. APHIS works closely with 

the USFWS to determine the application of protection measures and where those measures 

should be applied prior to any treatments. APHIS also evaluated the potential direct and 

indirect impacts to non-target species which is summarized in the final human health and 

ecological risk assessments for each insecticide.

APHIS would like to note that agencies are not required to publish concurrence letters as part of 

our NEPA documents. Coordination with other environmental reviews (50 CFR § 402.06) says, 

“. . . the results should be included in the documents required by those statutes.” To reduce 

paperwork and an emphasis on background material (40 CFR § 1500.4), we make biological 

assessments part of the administrative record available through FOIA. APHIS complied with the 

applicable publication requirements for the programmatic EIS and all tiered EAs, consequently 

reopening public comment periods will not alleviate any perceived deficiency in public access 

and does not provide any additional remedy for NEPA compliance. 

The 1998 ESA Handbook provides guidance for completing consultations. More recent guidance 

at https://www.fws.gov/endangered/what-we-do/faq.html#10 says, “Formal consultation should 

be initiated prior to or at the time of release of the DEIS or EA. At the time the Final EIS is

issued, section 7 consultation should be completed.” We discussed our Section 7 consultation 

work to date in the final EIS which included timely initiation of formal consultation and provided 

for compliance to occur at the State level until a programmatic Biological Opinion is in place 

Comment 157

APHIS received the following comment, “The EA cites to correspondences with FWS at 

Appendix 2, but Appendix 2 is blank”.

Local USFWS Section 7 consultations were entered into prior to the DRAFT EA. USFWS 

verbally indicated concurrence and stated the letter of concurrence regarding the local site 

specific biological assessment was being written and sent for signature. The Final EA will have 

the letters of concurrence cited in the Appendix 2. See Appendix 2.

Comment 158

APHIS received the following comment, “Because the site specific project is vague and fails to 

describe the breadth of cumulative effects it cannot comply with the ESA or NEPA. Any 

discrepancy between the project described in the EAs and the documents provided to the U.S. 

Fish and Wildlife Service must be rectified.”

APHIS believes that the site specific information described in the draft EA is adequate to allow 

completion of Section 7 compliance with the USFWS. Information discussed in the draft EA is 
93

also shared with the USFWS during consultation so there is no discrepancy between actions 

described in the EA and other documents.

Comment 159

APHIS received the following comment, “APHIS would unlawfully be making an irreversible or 

irretrievable commitment of resources if it allows insecticide application on rangeland 

grasshoppers and/or Mormon crickets to occur prior to receipt of a final biological opinion from 

FWS. APHIS will run afoul of its Section 7 ESA requirements if it chooses to move forward, and 

it will also likely violate the ESA’s prohibition against the take of endangered species as 

described by Section 9 of the statute if it moves forward with this project prior to properly 

completing its Section 7 duties. Even where there is a letter of concurrence, APHIS would still 

fail to comply with the ESA because informal consultation does not authorize the incidental take 

of federally-listed species nor does it authorize the adverse modification or destruction of critical 

habitat, and the letter of concurrence fails to articulate any rationale for the buffers.”

APHIS has been able to complete informal consultation with the USFWS regarding the APHIS 

Grasshopper Program at the State level. Formal consultation has not been required since the 

USFWS has concurred with the APHIS determinations of not likely to adversely affect, including 

any associated critical habitat. Since APHIS has complied with Section 7 through informal 

consultation APHIS has not violated Section 9 of the ESA, nor has formal consultation been 

required resulting in a biological opinion.

The commenter errs in assuming that any of APHIS’s projects will result in “incidental take” 

since the agreed-upon mitigation measures, included in Appendix 3 of each EA, were developed 

to preclude such. Neither will APHIS projects modify or destroy critical habitat. Quite the 

contrary, the failure to suppress severe grasshopper infestations pose the real inherent risk of 

“take” of T&E species and “adverse modification or destruction of critical habitat” due to 

overfeeding, often causing defoliation of nurse plants and consumption of sensitive plants, 

themselves.

Comment 160

APHIS received the comment “The Wyoming toad is highly sensitive to pesticides, and are 

greatly imperiled by any acute or subacute contact with pesticides. In addition, any impacts to 

their insect prey are must be considered direct effects to these species”.

As stated on page 19 of Appendix 3, it is not likely that APHIS grasshopper suppression 

activities will occur in the vicinity of Mortenson Lake where Wyoming toads are found. If 

suppression activities are conducted in Albany County then the following impact minimization 

efforts will be put into place: A one mile buffer for aerial spray shall be maintained on each side 

of the Little Laramie River and no treatments will be applied within a one mile buffer of 

Mortenson NWR. See USFWS concurrence letter in Appendix 2.

Comment 161

APHIS has received the following comments, “Grasshopper spraying in or near riparian areas 

can decrease prey populations for these species as well as produce chronic sub-lethal effects as a 

result of drift or ingesting pesticide through the insects they consume” in reference to the 
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Southwestern willow flycatcher (Empidonax traillii extimus) and “for all these species, 

insecticide spraying threatens their food supply and imperils them with acute and subacute 

poisoning impacts” in reference to “the Interior Least Tern (Sterna antillarum athalassos), the 

Piping Plover (Charadrius melodus), the Western yellow-billed cuckoo (Coccyzus americanus 

occidentalis), and the Whooping Crane (Grus Americana)”. 

Protective measures were developed during the lengthy local USFWS Section 7 consultations

for each of the 37 T&E species and species of concern within proposed treatment areas. APHIS 

protective measures were determined using the USFWS Recommended Protection Measures for 

Pesticide Applications in Region 2 of the U.S. Fish and Wildlife Service” (USFWS 2007). The 

USFWS letters of concurrence agree with our determinations. See Appendix 3 page 24 Platte 

River Species and Appendix 3 page 14 for YBCO. See also Appendix 2 for USFWS concurrence 

letter. 

Comment 162

APHIS received the comment “The threatened Western DPS is found west of the Continental 

Divide through the Rocky Mountains in the United States and in Wyoming”.

APHIS cannot adequately reply to the commenter at this time. Without an explanation of the 

meaning of the acronym “DPS” and/or a scientific name of the species, APHIS is uncertain as to 

what the commenter is referring. 

Comment 163

APHIS received the comments “Wyoming’s listed fish are already facing significant threats from 

climate change and habitat loss. Insecticide use threatens them with direct effects, and also 

imperils their food supply. Most of these species have a limited range, and if insecticides were to 

poison their waters due to a single unexpected gust of wind or bad judgement call by an 

applicator, they would have nowhere else to go to survive. Bioaccumulation of toxins in their 

limited range, both from this project and other activities such as farming, mining, grazing, and 

OHV use, presents a substantial threat that must be considered for these precariously endangered 

fish” in reference to “the Bonytail vhub (Gila elegans), the Colorado pikeminnow (Ptychocheilus 

Lucius), the Greenback cutthroat trout (Oncorhynchus clarkii stomias), the Humpback chub 

(Gila cypha), the Kendall Warm Springs dace (Rhinichthys osculus thermalis), the Pallid 

sturgeon (Scaphirhynchus albus), and the Razorback Sucker (Xyrauchen texanus)”.

The greenback cutthroat trout (Oncorhynchus clarkii stomias) has not been found in Wyoming 

according to USFWS surveys and is only known from high elevation locations in Colorado. 

Since this species is found at high elevation it is unlikely to move into Wyoming. See Appendix 3 

pages 24 Platte River Species, page 25 Colorado River Species and page 15 for KWSD. See also 

Appendix 2 for USFWS concurrence letter and response to comment 161.

Comment 164

APHIS received the comment “The Western Glacier stonefly is already highly imperiled due to 

climate change and any exposure to insecticides would be a fatal blow to this species”.
95

As stated on page 20 of Appendix 3, it is not likely that APHIS grasshopper suppression 

activities will occur in areas of the stonefly’s habitat, riparian areas due to a programmatic 

buffer placed on either side of streams or water bodies. This 500 foot buffer is standard 

procedure for all USDA APHIS PPQ grasshopper aerial suppression programs. For those areas 

that may be treated using ground equipment the 50 foot buffer will be increased to 500 feet 

around waters and riparian areas that are Western Glacier Stonefly suitable habitat, within the 

range of the species. See USFWS concurrence letter in Appendix 2.

Comment 165

APHIS received the comments, “Impacts to these mammal species must be studied before this 

project may move forward. Several of these species can occupy the very rangelands this EA 

targets, or may pass through it. Impacts of spraying can include habitat disturbance, acute and 

subacute poisoning, and reduced prey, amongst other possible impacts that must be considered” 

in reference to “the Black-footed ferret (Mustela nigripes), the Canada lynx (Lynx canadensis), 

the Grizzly bear (Ursus arctos), the Northern Long-eared bat (Myotis septentrionalis), the 

Preble’s meadow jumping mouse (Zapus hudonius preblei), and the Wolverine (Gulo gulo) 

(proposed)”.

The North American wolverine (Gulo gulo luscus) is a proposed species and under USFWS 

Section 7 Act there is no requirement to consult on proposed or candidate species. (See USFWS 

letter of concurrence in Appendix 2.) For other species listed in these comments see Appendix 3 

pages 16, 17, 12, 13, and 18 respectively. See also Appendix 2 for USFWS concurrence letter 

and response to comment 161.

Comments 166

APHIS received the comments, “Use of insecticides can directly effect plants and it may also 

harm their soil and reduce available pollinators for these plants, threatening the viability of their 

life cycle. Any mitigation efforts to avoid adverse effects to ESA listed plants will necessitate 

knowledge of all occupied habitat, which requires regular surveys, and also knowledge of 

groundwater, as well as knowledge of unoccupied but nonetheless essential habitat. This 

knowledge would also have to factor in current and anticipated threats, cumulative impacts, and 

likely climate change migration. Any take of these plants is illegal” in reference to Blowout 

penstemon (Penstemon haydenii), Colorado butterfly plant (Gaura neomexicana ssp. 

Coloradoensis), Desert yellowhead (Yermo xanthocephalus), Ute Ladies’-tresses (Spiranthes 

diluvialis), and Western Prairie fringed orchid (Platanthera praeclara).

Colorado Butterfly Plant (Gaura neomexicana coloradensis) has been delisted and no longer 

receives protection under the ESA. For other species listed in these comments see Appendix 3 

pages 22, 23, 21 and 24 respectively. See also Appendix 2 for USFWS concurrence letter and 

response to comment 161.

Comment 167

APHIS received the comments, “APHIS recognizes that malathion causes low to moderate 

toxicity in terrestrial plants, with effects on reproduction, growth, and mortality. In all cases, use 

of insecticides may reduce available pollinators for these plants, threatening the viability of their 

life cycle. No mitigation measures can work to protect this plant unless APHIS is entirely 
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confident that it knows all locations of this species and that no changes have occurred” in 

reference to Ute ladies’-tresses. 

Ute ladies’-tresses typically blooms from late July through August. APHIS strives to use 

preferred chemicals and strategies for treatments in Wyoming and under these preferred 

methods would be finished with treatments by late July. If treatments are necessary later than 

July, then APHIS strictly follows program guidelines and USFWS consultations. See Appendix 3 

page 21 and Appendix 2.

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Appendix 7: 2019 Adult Grasshopper Survey Map
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Appendix 8: Completed FONSI
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