SECTION 18 EMERGENCY EXEMPTION REQUEST 

For the State of Wyoming - 2010 

TYPE OF EXEMPTION – SPECIFIC 

CONTACT PERSON(S) AND QUALIFIED EXPERT(S) (166.20(a)(1)) 

CONTACT PERSON: QUALIFIED EXPERT: 

Name: Polly Cross Name: Terri Hass 

Title: Assistant Manager Title: Technical Manager 

Organization: Wyoming Dept. of Organization: Chemtura Corp. 

 Agriculture 

Address: 2219 Carey Ave. Address: 199 Benson Road 

 Cheyenne, WY 82002 Middlebury, CT 06749 

Phone: 307-777-6590 Phone: 203-573-2027 

Fax: 307-777-6593 Fax: 203-573-2610 

Email: pcross@state.wy.us Email: terri.hass@chemtura.com
DESCRIPTION OF PESTICIDE REQUESTED (166.20(a)(2)) 

Common Chemical Name 

(Active Ingredient): diflubenzuron 

Trade Name(s) and 

EPA Reg. Number: Dimilin 2L, EPA Reg. #400-461

Formulation: % Active Ingredient: 2 lbs. A.I./gallon 

Manufacturer(s): Chumtura Corp. 

DESCRIPTION OF PROPOSED USE (166.20(a)(3)) 

Sites to be Treated: All counties in Wyoming where Mormon crickets and grasshoppers 

have or may occur. 

Method of Application: Application by aerial and ground equipment only is requested. 

Application through irrigation equipment is prohibited. 

Rate of Application: 2 fl. Oz of Dimilin 2L 

Maximum Number of Applications: Do not exceed 2 fl. Oz. of Dimilin 2L per acre per 

cutting, or a total of 4 fl. Oz per growing season. Wyoming alfalfa hay fields are harvested 

2-4 times per growing season, depending on the elevation. Lower elevations have as 

many as 4 cuttings, with higher elevations typically having only 2 cuttings, due to the 

shortened growing season. 

Total Acreage (or other units) to be Treated: All alfalfa hay acreage (550,000 acres) 

could potentially suffer grasshopper or Mormon cricket outbreaks. Due to proximity to 

extensive federal lands, it is anticipated that 6% of the hay ground could be severely 

impacted and require treatment. Acreage to be treated is anticipated to be 26,000 acres. 

Total Amount of Pesticide to be Used: At 2 fl oz of product applied to 26,000 acres of 

alfalfa (assuming the maximum of two applications per acre) would require 407 gallons 

(814 lbs. a.i.) of Dimilin 2L. 

Use Season: The first applications would be made after May 1st and the last applications 

would be made no later than October 31st, 2010. 

Additional Restrictions. User Precautions and Requirements. Qualifications of 

Applicators, etc: 

This application is being submitted for USDA/APHIS/PPQ and Wyoming Weed & Pest 

Districts. Private sector use will be very minimal. 

Dimilin 2L is not effective in controlling Mormon crickets or grasshoppers once they reach 

the adult stage. 

All applicable restrictions, directions and precautions on the Federal Label and Section 18 

use directions must be followed. 
Applications are to be made in accordance with the USDA/APHIS rangeland grasshopper 

suppression program. 

ALTERNATIVE METHODS OF CONTROL (166.20)(a)(4)) 

Several chemical controls for grasshoppers and crickets are available in Wyoming, but all 

available products for control have minimal residual activity. There are at least 6 species 

of grasshoppers with overlapping generations and emergence dates, which results in 

multiple applications per generation for control of the various species hatching at different 

times throughout the season. Regulations prohibiting more than one application and/or 

prohibitive cost of multiple applications make these options ineffective. Non-selectivity 

toward beneficials, which could reduce predator populations, is another negative impact of 

all registered products. For specific explanations, see below. 

The following products are registered, but have shortcomings that make them inadequate 

for control for the indicated reasons. “Most of the registered insecticides currently 

registered for grasshopper control are not effective, are toxic to beneficial arthropods, or 

provide only short residual control of grasshoppers necessitating multiple pesticide 

applications.” 

Carbaryl (Sevin): It is effective, but two to three applications would be necessary for 

seasonal control. The label directions state only one application per year. This product is 

detrimental to beneficial insects. 

Chlorpyrifos: It is an effective product, but the two to three applications are required. It is 

also more expensive than carbaryl and could not be used in an alfalfa hay cropping 

system without eliminating the profit margin. This product is detrimental to beneficial 

insects. Not in USDA/APHIS/PPQ Environmental Impact Statements so not an option for 

their use. 

Lambda-Cyhalothrin (Warrior): 7-10 day residual (requiring two to three treatments for 

control) $7.60-$9.90/acre. This product is also more expensive than carbaryl. . This 

product is detrimental to beneficial insects. Not in USDA/APHIS/PPQ Environmental 

Impact Statements so not an option for their use. 

Methyl parathion (generic): The length of residual on the crop is very short (24-48 hour 

residual), requiring multiple treatments at $8.00/acre. More expensive than carbaryl and 

requires more treatments than alternatives due to short residual. . This product is 

detrimental to beneficial insects. Not in USDA/APHIS/PPQ Environmental Impact 

Statements so not an option for their use. 

Malathion: Very short period of residual activity. Three to four applications would be 

necessary for control, making the product more expensive than other alternatives. . This 

product is detrimental to beneficial insects. 

Dimilin provides early season control without subsequent spraying. It has been proven 

effective in grasshopper control. It has a greater than 30-day residual on treated foliage 

and does not impact non-target beneficial insects. These qualities make the product 

unique in controlling outbreaks of multiple species of grasshopper throughout the growing 

season. All alternative products have a period of residual control of between two and ten 

days, necessitating repeat applications. The cost of these multiple applications in low 
rainfall areas are cost prohibitive requiring growers to make a decision of whether to 

control grasshoppers and lose any hope of profit or lose the crop from feed damage. 

Dimilin’s longer period of residual activity provides a longer control window which allows 

for the control of delayed hatching nymphs, later hatching grasshopper species, and 

secondary infestations, negating the need of additional applications prior to harvest of the 

foliage for hay. When a grasshopper nymph is exposed to Dimilin, it is unable to 

successfully molt. Dimilin also demonstrates transovarial activity that can weaken or 

prevent hatching of subsequent populations. Grasshoppers that succeed in molting may 

exhibit deformity that could contribute to slower movement, limited jumping, reduced 

feeding and lack of ability to fly. Any adult/nymph exhibiting these symptoms would more 

likely be susceptible to predatory and/or parasitic insects (that would be eliminated by the 

use of other products). 

Biological Control: Natural-occurring pathogens have shown little success and often, 

complete failure, even if successful, they are not commercially available. Surveys were 

conducted with Nosema Locustae that did show some effectiveness on small instars. 

However, when looking at infestations that are being predicted for Wyoming in 2010, using 

this type of control would not be effective or economical feasible.

EFFICACY OF USE PROPOSED UNDER SECTION 18 (166.20(a)(s)) 

Chronic dietary exposure, including drinking water, was evaluated for the U.S. population 

and various population subgroups including infants and children. One-day single dose 

oral studies in rats and mice indicated there were no significant acute effects observed. 

As only marginal effects were noted, an acute exposure assessment is not needed for 

diflubenzuron. 

Dietary Exposure from diflubenzuron was estimated based on the average residue 

values from the currently labeled raw agricultural commodities (RACs), and from the 

proposed uses on pear, nut crops, pistachios, stonefruits (except cherries), peppers, and 

alfalfa. Percent of crop treated was also factored into the estimate. Residues in meat, 

milk and egg products were obtained from extrapolation of metabolism study data to 

anticipated livestock dietary burdens. The dietary exposure analysis was estimated based 

on 1989-92 USDA food consumption data. For the U.S. population (total), the dietary 

exposure of diflubenzuron was estimated as 0.000157 mg/kg/day. For nursing and nonnursing infants, the exposure was estimated as 0.000140 and 0.000410 mg/kg/day, 

respectively. For children, the exposure was 0.000343 and 0.000219 mg/kg/day for 1-6 

year olds and 7-12 year olds, respectively. 

The dietary exposure from p-chloroaniline and 4-chlorophenylurea (CPU), which have 

been detected in some food products, was also determined. Average residues or 1⁄2 LOQ 

from field trials for mushrooms, rice, pears, almonds, pecans, stonefruits (peaches, 

prunes, plums), and peppers were used. Residues in meat, milk, and eggs were obtained 

from extrapolation of metabolism data to anticipated livestock dietary burdens. The 

percent treated of each crop was also factored into the exposure estimate. For the U.S. 

population (total), the dietary exposure of PCA and CPU was estimated at 0.000001 

mg/kg/day and 0.000017 mg/kg/day, respectively. 

Drinking Water: Diflubenzuron degrades in soil relatively quickly with an aerobic half-life 

ranging from 3-7 days. Major degradates include difluorobenzoic acid (DFBA) and CPU. 

DFBA is further metabolized through decarboxylation and ring cleavage by soil microbes 

whereas CPU is slowly degraded to soil-bound entities. Under anaerobic aquatic 

conditions, diflubenzuron has a half-life of 34 days with the main degradates being DFBA 
and CPU. In surface water, diflubenzuron is degraded by microbes with a half-life of 5-10 

days. 

The soil mobility of diflubenzuron is considered quite limited based on a number of 

experimental studies as well as by computer modeling. CPU has also been shown to be 

relatively immobile in soil. Although DFBA shows mobility in soil, it is rapidly degraded. 

Therefore, based on results of laboratory and field studies, it is not likely that diflubenzuron 

or it’s degradates will impact ground water quality to any significant extent. 

The Drinking Water Level of Concern (DWLOC) for chronic (non-cancer) exposure to 

diflubenzuron in drinking water was determined as 695 ppb for the U.S. population (total) 

and 197 ppb for infants and children. The DWLOC for chronic (cancer) exposure to CPU 

in drinking water was determined as 1.7 ppb for the U.S. population (total). Based on SCIGRO and Tier II PRZM-EXAM modeling, estimated residues of diflubenzuron in ground 

and surface water are not expected to exceed 0.0023 ppb and 0.09 ppb, respectively, and 

residues of CPU in ground and surface water are not expected to exceed 0.065 ppb and 

0.23 ppb, respectively. Because PCA is only a minor metabolite in the environment, it is 

not considered in the drinking water assessment. The estimated concentrations of 

diflubenzuron and CPU in ground and surface water are less than the DWLOCs as a 

contribution to chronic aggregate exposure. 

Non-dietary exposure. Diflubenzuron is a restricted use pesticide based on its toxicity to 

aquatic invertebrates. This restricted use classification makes it unavailable for use by 

homeowners. Occupational uses of diflubenzuron may expose people in residential 

locations, parks, or forests treated with diflubenzuron. Based on very low residues 

detected in forestry dissipation studies, a low dermal absorption rate (0.5%), and 

extremely low dermal and inhalation toxicity, these uses are expected to result in 

insignificant risk, and are therefore not included in the aggregate risk assessment. 

Cumulative Effects

Compton Chemical has considered the potential for cumulative effects of diflubenzuron 

and other substances with a common mechanism of toxicity. The mammalian toxicity of 

diflubenzuron is well defined. We are not aware of any other pesticide product registered 

in the United States that could be metabolized to p-chloroaniline. For this reason, 

consideration of potential cumulative effects of residues from pesticidal substances with a 

common mechanism of action as diflubenzuron is not appropriate. Thus, only the potential 

exposures to diflubenzuron were considered in the total exposure assessment. 

Safety for U.S. Population

The total non-occupational aggregate exposure from diflubenzuron would occur from food 

and drinking water routes. Based on the 0.02 mg/kg/day RfD (reference dose) derived 

from the dog chronic NOEL of 2 mg/kg/day and a 100-fold safety factor, chronic dietary 

exposure to the U.S. population (total) is 0.8% of the RfD. Aggregate exposure does not 

exceed 100% of the RfD when the potential theoretical residues in drinking water are 

included. 

The total non-occupational aggregate exposure from PCA would occur from the dietary 

route. The risk from diflubenzuron-derived PCA can be estimated using a linear 

extrapolation of the dose-response from the rat chronic study conducted by the National 

Toxicology Program in which rats were dosed via gavage with p-chloroaniline 

[hydrochloride] for 24 months. EPA has determined the q1* as 0.112 based on the 

combined incidence of liver adenomas and carcinomas in male mice. Using this q1*, the 

theoretical risk to the U.S. population (total) from dietary exposure to diflubenzuronderived PCA was estimated at 8.18 x 10-8.

 
For CPU, total aggregate exposure could occur from food and drinking water. The EPA 

has determined that since CPU is structurally related to monuron, the most potent Q1* of 

1.52 x 10-2 (based on male rat liver neoplastic nodule and/or carcinoma combined tumor 

rates) from the NTP carcinogenesis data for monuron should be used for assessing 

cancer risk from CPU. Using this Q1* the theoretical risk to the U.S. population (total) 

from dietary exposure to CPU was estimated at 2.51 x 10-7. The aggregate cancer risk 

including drinking water does not exceed the level of concern. 

Safety for Infants and Children 

 The chronic dietary exposure of diflubenzuron of nursing and non-nursing infants is 0.7% 

and 2.0% of the RfD, respectively, and for children 1-6 and 7-12 years old is 1.7% and 

1.1% of the RfD, respectively. Aggregate exposure does not exceed 100% of the RfD 

when the potential theoretical residues in drinking water are included. 

 

The NOEL for maternal and developmental toxicity in rats and rabbits were greater than 

1,000 mg/kg/day, and the NOEL for reproductive toxicity was greater than 5,000 

mg/kg/day. Therefore, based on the completeness and reliability of the toxicity data and 

the conservative exposure assessment, there is reasonable certainty that no harm will 

result in infants and children from aggregate exposure to residues of diflubenzuron and its 

conversion products containing the p-chloroaniline moiety. 

Safety to beneficial insects 

DIMILIN 2L is not hazardous to bees when used alone. Apiarists in Wyoming have seen a 

significant decrease (25% - 33%) in bee numbers over the last few years. All other 

products that are labeled for grasshoppers and Mormon cricket control in alfalfa and hay 

fields are detrimental to bee population. To use products other then Dimilin 2l would 

jeopardize the apiary industry in the state of Wyoming. (Wyoming Apiarists were sent questioners 

over the last two years to determine bee losses in the state.) 

ENFORCEMENT PROGRAM (166.20(a)(10)) 

Although Wyoming does not have enforcement primacy at this time, the department has 

two (2) full-time and one (1) part-time pesticide enforcement inspectors, which will enable 

us to enforce the restrictions under Section 18. All inspection records will be available to 

EPA Region VIII inspectors for any additional monitoring they deem necessary. 

REPEAT USES (166.20(a)(11) 

Wyoming’s requested the use of Dimilin 2L on alfalfa to control grasshoppers and Mormon 

crickets in 2005. This application is being submitted for USDA/APHIS/PPQ and Wyoming 

Weed & Pest Districts. Use from Private applicators will be very minimal. The 2010 

request is due to projected numbers from USDA/APHIS/PPQ. PPQ projects an outbreak 

of grasshoppers from 15 + per square foot depending on location within the state and 

weather conditions this spring. The action threshold lever for grasshoppers in Wyoming is 

8 insects per square yard. In 2009 numerous counties in the state of Wyoming reported 

as high as 50 insects per square yard. If PPQ is correct in their projections, the 

devastation within several counties in Wyoming could be at astronomical proportions. 

Rangeland areas being sprayed by APHIS/PPQ and Weed and Pest Districts have alfalfa 

fields located within the spray area or adjacent to them. To spray rangelands and not 

include alfalfa fields that are located within the rangeland or adjacent to them would only 

give a safe haven to grasshoppers and Mormon crickets causing more damage and 

economic losses to Wyoming alfalfa producers. 
PDF FILES: 1. Wyoming Adult Grasshopper survey 2009 

 2. Wyoming Adult Grasshopper survey 2008 

PROGRESS TOWARD REGISTRATION (166.25(a)(2)) 

The 1R-4 08678 diflubenzuronialfalfa residue study was initiated in 2004. This study 

consists of a total of 4 field trials (1 in Idaho, 1 in Washington, I in California and 1 in 

Colorado). Two treatments were included in the study. Treatment 02 consisted of 

applications of diflubenzuron at 0.0325 lb ai/A one day before sample cutting of forage and 

hay for a total of 3 applications and 3 cuttings. Treatment 03 consisted of three 

applications of diflubenzuron at 0.0325 lb ai/A, at 14 day intervals with the last application 

1 day before the collection of seed samples. The samples in this study have been 

analyzed (see attached summary of residues) and the analytical summary report has been 

received at IR-4 Headquarters. Diflubenzuron parent residues in forage samples after the 

third cutting ranged from 0.824 to 2.890 ppm. Diflubenzuron parent residues in hay 

samples after the third cutting ranged from 2.608 to 9.072 ppm. Diflubenzuron parent 

residues in seed samples ranged from 0.056 to 0.434 ppm. A second study (A8678) was 

initiated in 2008 to include analysis of metabolites (CPU and PCA) and storage stability 

samples. These samples have not been analyzed yet. 

Below is the residue test application scenario: 

PCR: 0.0325 LB.AI/A; AERIAL APPLIC: 1-5 GAL/A; GROUND APPLIC: 20-30 GAL/A; 

ONE APPLIC/CUTTING; 14 DAY PHI 

Protocol: (THE 2008 PROTOCOL A8678 WILL COMPLETE THE STUDY, ADDING 

ANALYSIS OF METABOLITES AND STORAGE STABILITY) 0.0325 LB AI/A; MAKE A 

SINGLE BROADCAST APPLIC IN 20-30 GPA AT 1-DAY BEFORE EACH OF 3 FORAGE 

AND HAY SAMPLE CUTTINGS; AND MAKE 3 BROADCAST APPLIC IN 20-30 GPA AT 

14-DAY INTERVALS, WITH A 1-DAY PHI FOR SEED; FOR ALL TREATMENTS 

INCLUDE 1 PT/A EMULSIFIED VEGETABLE OR PARAFFINIC CROP OIL 

Also see Attachment IR-4 08678/ Diflubenzuron /Alfalfa 

NAME OF PEST (166.209(b)(1)) 

Scientific Name: Approximately 120 species (mainly Acrididae family, a few 

Tettigoniidae)

Common Name: Grasshopper 

Scientific Name: Anabrus simplex

Common Name: Mormon cricket 

DISCUSSION OF EVENTS OR CIRCUMSTANCES WHICH BROUGHT ABOUT THE 

EMERGENCY CONDITION (166.20(b)(2)) 

Grasshoppers are a historic threat to all crops. The Mormon cricket is not a true cricket. 

The insect resembles more a lifestyle of a grasshopper. Mormon crickets are of economic 

importance in the fact that they destroy plants on rangeland, cropland, and vegetable 

gardens. Male and female Mormon crickets are large insects and can reach lengths of two 

and one-half inches during the adult stage. The female Mormon cricket is distinguished by 

the long ovipositor that also looks like a type of "stinger" located at the end of the 

abdomen. The male lacks this ovipositor. The Mormon cricket can be economically 

devastating. 
 

It has been calculated that a Mormon cricket, at a density of one per square yard, can 

consume 38 pounds of dry weight rangeland forage per acre. The Mormon cricket 

destroys sagebrush, alfalfa, small grains, seeds, grasses, and vegetable crops. In the 

past, conventional tillage, summer fallow and burning have worked to control infestations. 

Occasionally, there would be a mild winter which allowed grasshopper nymphs to survive 

the winter and multiply to economic thresholds. This would bring on area wide treatments 

and emergency control measures. The spring of 2010 has been warmer than average 

throughout most of the state and pressures from both Mormon crickets and grasshoppers 

is already mounting. Fremont, Goshen and Niobrara County in Wyoming are major 

producers of alfalfa hay and grass hay in the state. Niobrara County was also one of the 

counties that were hardest hit in 2009, reporting losses up to 90% of all crops due to 

grasshopper and Mormon cricket infestation. 

 

Registered pesticide alternatives with some activity on grasshoppers also control a wide 

variety of beneficial insects. The available pesticides are short-lived in the environment 

and require multiple applications to control a single generation of grasshoppers or Mormon 

crickets. Available insecticides only control the adult insects and the next generation 

expands quickly to economically significant numbers, requiring multiple applications. 

Predatory insects, which provide good control without the need of chemical controls for the 

aphid, do not exist for the grasshoppers and Mormon crickets. 

The economic effects from grasshoppers are expected to be disastrous, due to the 

warmer winter this year and the warm, moist spring. The moisture has provided 

vegetation for the nymphs to grow and grasshoppers are becoming a major problem. 

Dimilin has shown longer effectiveness without harming beneficial insects. The increased 

length of control coupled with the “safer” technology will gain the producers more 

integrated pest management, and longer term control. 

For the 2010 crop years USDA/APHIS/PPQ has made projections of 15 + grasshoppers 

per square yard in alfalfa producing counties in the state. The state relies on information 

supplied by USDA/APHIS/PPQ for grasshopper population densities. APHIS has 

reported that their survey in 2009 consisted of 1,631 stops statewide between the dates of 

7/01/2009 and 9/3/2009. Survey stops were collected by APHIS employees using the (18 

sq. foot)/2 method. Protocol for survey is attached for complete survey collection 

information. 

PDF FILES: 1. Assessing Rangeland Grasshopper Populations (Protocol for 

 survey) 

2. Wyoming Adult Grasshopper Survey 2009. 

3.Wyoming Adult Grasshopper Survey 2008 for previous year survey 

numbers. 

Control strategies. 

The new levels of pest pressure, combined with the multiple species/extended nymphhatching characteristics of grasshoppers, results in growers being faced with pest 

pressure over longer periods of time. Alfalfa hay growers are faced with low prices for 

their crop and the cost of making multiple applications for grasshopper control will remove 

any likelihood of the growers making any profit. Due to the short residual of available 

pesticides growers would suffer significant crop losses from insect migration from 

surrounding ground that was not treated. Within a few days of treatments, the currently 

available products will not offer any further protection and the crop is vulnerable to 

extensive damage from migrating grasshoppers and Mormon crickets. The combination of 

cost of product, costs of multiple application and crop losses (including contaminated hay 

with insect carcass) have created an urgent, non-routine situation. 
EXPECTED RESIDUE LEVELS IN FOOD (166.20(a)(6)) 

Chemtura Corp. has conducted two separate residue studies on fresh and dried grass 

treated with Dimilin. Tests were conducted in a total of nine locations, one each in 

Wyoming, North Dakota, Nebraska, California, Pennsylvania, Florida, Oklahoma, South 

Dakota and Montana. The Dimilin was applied either by ground or aerially. Applications 

were made using 2 oz. or 1 oz. of formulated product in a total spray volume of one quart. 

Fresh grass samples were harvested at 2 hours following application of the Dimilin. Dried 

grass samples were also obtained from the residue test plots. 

Residues of diflubenzuron were determined using high-pressure liquid chromatography. 

The LOQ was determined to be 0.05 ppm. 

Residues of diflubenzuron in fresh and dried grass treated with Dimilin had residues of: 

 Fresh grass – 2 oz. appl. = 0.24 – 3.82 ppm 

 1 oz. appl. = 0.06 – 5.47 ppm 

 Dried grass – 2 oz. appl. = 0.41 – 5.68 ppm 

 1 oz. appl. = 0.63 – 5.11 ppm 

DISCUSSION OF RISK INFORMATION (166.20(a)(7)) 

Diflubenzuron is not toxic to mammals, birds, terrestrial vertebrates, fish, mollusks, or 

plants. Although diflubenzuron is toxic to certain sensitive aquatic invertebrates, alfalfa in 

Wyoming is not grown in the vicinity of any listed aquatic invertebrate. Dimilin 2L is applied 

at very small use rates (2 ounces per acre) and is sprayed in bands, with equal amounts of 

untreated ground between the treated bands (Reduced Area & Agent Treatment - RAAT). 

Therefore, the use of Dimilin 2L on alfalfa is not expected to adversely affect endangered 

or threatened species. 

COORDINATION WITH OTHER AFFECTED FEDERAL, STATE, AND LOCAL 

AGENCIES (166.20(a)(8)) 

The U.S. Fish and Wildlife Service, Wyoming State Office and the Wyoming Game & Fish 

Department will be provided a copy of this request. Comments will be forwarded to the 

Agency. 

NOTIFICATION OF REGISTRANT (166.20(a)(9)) 

Chemtura Corp. has been contacted concerning this application and has agreed to 

support the request. (See attached letter of support.) 

DISCUSSION OF ECONOMIC LOSS (166.20(b)(4)) 

Hay is by far the leading crop in Wyoming in terms of value of production. Drought 

conditions reduced the value of Wyoming hay products $202 million in 2007 and 2008, but 

the market maintained its leading status due to demand for alfalfa in the two largest 

agricultural commodities in the state – sheep and beef cattle. Dairy quality alfalfa receives 
the highest price and is sold throughout the state, and region. Dairy quality alfalfa has 

also been shipped as far as Texas and Kentucky. Alfalfa is harvested from two to four 

times per year, depending upon the elevation, with higher altitudes producing lower yields. 

On irrigated fields in lower elevations over seven tons per acre of alfalfa can be harvested. 

Mormon crickets and grasshoppers extensively impact the producer’s bottom line, either 

from crop damage or from chemical costs in controlling the insects. The quality of the 

alfalfa is also an important consideration from an economic standpoint. Damaged hay will 

be downgraded from dairy quality, known as “Supreme” and “Premium” to only “Good” or 

“Fair”. Most of the nutrition is in the leaves, so alfalfa hay with a higher percentage of 

stems is not acceptable to dairies, which require the maximum nutritional value. Alfalfa 

hay that has lost 20% or more leaf material will be used to mix with other feeds as filler, or 

used as a supplemental feed for grazing livestock and is currently only worth about $55-

$60 per ton. A change in classification results in losses of $60 - $45 per ton. At 10% 

damage and a downgrade in classification to $68 per ton would result in lost revenue to 

the grower. 

Without Dimilin 2L, each cutting in the affected areas is expected to suffer losses of 10% 

or greater. The first cutting is generally the largest crop harvested and is also hit the 

hardest by Mormon crickets and grasshoppers. Mormon crickets usually don’t affect the 

later crops as much, because they have finished their life cycle. Grasshopper damage will 

continue throughout the growing season until frost kills the hay or the grasshopper life 

cycle is completed and they die. 

Without the use of Dimilin 2L on alfalfa and pasture ground, we anticipate approximate 

losses of $4,522,180.00 (26,000 acres x $ 173.93, which is the difference between the 

high and low gross revenues in the chart) to alfalfa hay growers in Wyoming. 

THREATENED AND ENDANGERED SPECIES (Plants) 

Wyoming has one plant that is classified as endangered. The Blowout penstemon is 

located in 11 counties in Wyoming. Wyoming also has three other plant species that are 

classified as threatened: 1. Colorado Butterfly plant located in three counties; 2. Desert 

Yellowhead located in one county 3. Ute Ladies-Tresses located in 22 counties. The use 

of diflubenzuron instead of less environmentally safe pesticides that harm beneficial 

pollinators may insure the viability of these species. 

(Threatened and Endangered Species Info. from Wyoming US FWS web-site) 

PDF Files: 1. Blowout Penstemon 

 2. Colorado Butterfly plant 

 3. Desert Yellowhead 

 4. Ute Ladies-Tresses 

APIARISTS 

Using diflubenzuron in place of other approved pesticides that are harmful to bees and 

other beneficial pests also protects Wyoming Apiarists against further losses in revenue 

due to bee number decline. In 2008 Wyoming Apiarists saw a drop in honey production 

from 3,400,000 pounds in 2007 to 2,379,000 pounds in 2008. $181,000 decline in 

revenue to the states Apiary industry. According to Jerry Hayes - U.S. Beekeeping 

Report 50 years ago U.S. had 5 million hives; now about 2 million hives. 
Year Pounds 

(1,000) 

Price Value 

($1,000) 

2007 3,440 $100 $ 3,440 

2008 2,379 $137 $ 3,259 

(Information on honey stocks & price per pound were gathered from Wyoming Agricultural Statistics) 

ECONOMIC DATA (166.20(b)(1)) 

Year Acres Yield per 

acre 

(tons) 

Price per 

ton ($) 

Gross 

Revenue 

per acre 

Average 

Cost per 

acre 

Net 

Revenue 

per Acre 

2009 * 550,000 * 2.9 * $120.00 * $348.00 * $150.00 * $198.00 * 

2008 530,000 2.9 $118.00 $342.20 $150.00 $192.20 

2007 570,000 2.7 $109.00 $294.30 $150.00 $144.30 

2006 500,000 2.3 $101.00 $232.30 $150.00 $82.30 

2005 600,000 2.8 $75.00 $210.00 $150.00 $60.00 

AVERAGE 550,000 2.7 $104.60 $285.36 $150.00 $135.36 

w/ Dimilin 

2L 

550,000 2.7 $104.60 $285.36 $150.00 $135.36 

w/o 

Dimilin 2L 

at 10% 

damage 

550,000 2.4 $68 $160.80 $150.00 $10.80 

w/o 

Dimilin 2L 

at 15% 

damage 

550,000 2.3 $68 $156.40 $150.00 $6.40 

w/o 

Dimilin 2L 

at 20% 

damage 

550,000 2.1 $61 $128.10 $150.00 -$22.00 

All acreage, yield data and price per ton data were taken from the 2009 Wyoming Agricultural Statistic book 

* estimated 

Estimated costs of aerially applied RAATs treatments of carbaryl and 

diflubenzuron against rangeland grasshoppers, 

Treatment Specific Mix Chemical cost Application cost Total cost 

Strategy per acre per acre per acre 

 Protected protected protected 

RAATs carbaryl 8 fl oz + 0.70 0.78 1.48 

to 50% of acreage 8 fl oz H2O 

8 fl oz/acre treated per treated acre 

(0.25 lb AI/acre) TV = 16 oz 

RAATs carbaryl 12 fl oz + 1.04 0.78 1.82 

to 50% of acreage 1 2 fl oz H2O 

12 fl oz/acre treated per treated acre 

(0.375 lb AI/acre) TV = 24 oz 
RAATs diflubenzuron 0.75 fl oz + 0.63 Dimilin 0.78 1.57 

to 50% of acreage 10 fl oz oil + 0.16 Oil

0.75 fl oz/acre treated 20.25 fl oz H2O 0.79 Total 

(0.0117 lb AI/acre) per treated acre 

5.3g/acre treated TV = 31 oz 

Mean percentage control of grasshoppers treated with RAATs treatments 

Days after treatment (1)

Treatment Rate (2) 7 14 21 28 

 Fl oz 

diflubenzuron 0.75 - 50 61.4 c 95.0 b 97.6 b 98.5 a 

(60.2) (94.6) (97.6) (98.6) 

Carbaryl 8 - 50 84.8 b 87.9 c 89.7 c 89.5 b 

(85.9) (88.2) (89.8) (90.7) 

(1) Corrected for natural mortality (unadjusted values in parentheses). A one-way analysis of 

variance was performed on a rank transformation of the data. A Tukey multiple comparison 

test was used to separate means. Means in the same column followed by the same letter 

are not significantly different (P δ 0.05). The untreated check population decreased an 

average of 0.4% per day. 

(2) Fluid ounces of undiluted material applied/acre and percentage of acreage treated. 

Field studies comparing carbaryl, Malithion and diflubenzuron were conducted on 

rangeland. However, there is very little information regarding data comparisons on alfalfa. 

I have attached different studies for your informational review. 

1. Bran Bait or Liquid Insecticide Treatments for Managing Grasshoppers on 

Croplands Adjacent to Rangeland or Conservation Reserve Program Acreages 

2. Impact of Dimilin® on Nontarget Arthropods and Its Efficacy Against Rangeland 

Grasshoppers 

3. Field and Economic Evaluation of Operational Scale Reduced Agent and Reduced 

Area Treatments (RAATs) for Management of Grasshoppers on South Dakota 

Rangeland, 1997-1999 

4. Pest Management Strategic Plan for Western U.S. Alfalfa and Clover Seed 

Production (Special interest a. page 96 – TABLE Insect Management in Alfalfa 

and Clover seed. b. page 98 – TABLE - Biological control. c. page 99 - 

TABLE – Toxicity Ratings on Pollinators and Beneficial in PNW Alfalfa and Clover 

Seed)
INSECT GROWTH REGULATOR

SUSPENSION CONCENTRATE

Chemtura Dimil 2L

AGROSOLUTIONS -

RESTRICTED USE PESTICIDE

Due to toxicity to aquatic invertebrate animals. i

For retail sale to and use only by Certified Applkators„ or persons under their direct

supervision, and only for those uses covered by the Certified Applicator's certification.

SECTION 18 EMERGENCY EXEMPTION FOR ALFALFA AND MIXED GRASS/ALFALFA HAY

FOR USE ONLY WITHIN THE STATE OF WYOMING

It is a violation of Federal law to use this product in a manner inconsistent with its labeling.

FOR CONTROL OF GRASSHOPPERS AND MORMON CRICKETS IN ALFALFA AND MIXED GRASS/ALFALFA HAY

SITES AND ACREAGE TO BE TREATED:

ALFALFA AND MIXED GRASS/ALFALFA HAY

GRASSHOPPERS AND MORMON CRICKETS: For optimum results, apply DIMILIN 2L when grasshoppers/Mormon crickets have reached the 2' d to 3'

instar stage of development. ()NUN will not effectively control grasshoppers and Mormon crickets once they reach the adult stage.

Crops Pests

Application Rate

(fl oz/acre) Application Timing

Alfalfa and Mixed Grasshopper 0.75 - 2 Use 1 application on early instar (majority in the 2nd through 4th instar nymphal stages).

Grass/Alfalfa Hay For best results use high rate on heavy infestations or dense foliage.

Mormon

cricket

May be used in a RAATs (Reduced Area and Agent Treatment) application on early instars. A RAATs application is an IPM strategy that takes advantage of grasshopper movement and conservation biological control to allow Dimilin 21. to be applied on a reduced

treated area and at reduced rates, while sustaining acceptable control.

The rate range to use per acre and amount of area treated will depend on grasshopper/

Mormon cricket age, plant canopy and topography. Skip up to 50% of the infested area

(every other swath) and use the lower rate under uniform topography with early instar

ages and sparse vegetation. If the majority of the population is late instars, vegetation

is dense, terrain is considered rough, and conditions are hot during treatment, then the

coverage and rate of DIMILIN 2L should be increased up to a blanket (100%) coverage

with 1 fl oz per acre.

Applications may be made after each cutting of alfalfa. Do not apply more than three

applications per year.

DIMILIN will not effectively control grasshoppers and Mormon crickets once they reach the adult stage

Aerial application: For low/high volume application, apply in 2 to 10 gallons of water per acre. For ULV application, apply in a minimum of 12 fl. ozs.

total volume per acre.

Ground application: For low/high volume application, apply in 2 to 30 gallons of water per acre. For ULV application, apply in a minimum of 12 fl.ozs.

total volume per acre.

Regardless of application type, total spray volume used must ensure thorough coverage of the target crop. Aerial and ULV spray mixtures should

include an evaporation/drift retardant product at use rates prescribed on the specific product label, particularly when conditions are favorable for

water evaporation (e.g., high air temperature and/or low humidity). When using oil type evaporation/drift retardant products, be sure to maintain a

ratio of at least 2 parts water to 1 part oil.

For low volume and ULV applications, make sure that the spray mixture in the boom contains the correct concentration of Dimilin 2L before application begins, and be sure that good agitation is maintained throughout mixing and application.

Do not exceed 2 fl. oz. per acre.

Do not apply closer than 14 days prior to harvest.

Do not apply DIMILIN directly to or allow to drift to water or wetlands.When disposing of equipment wash water or rinsate, do not contaminate water.

Do not plant food or feed crops in DIMILIN treated soils within 1 month following last application, unless DIMILIN is authorized for use on these crops.

Do not enter or allow workers into treated area during the restricted entry interval (REI) of 12 hours.

Do not apply within 25 feet by ground or within 150 feet by air of bodies of water such as lakes, reservoirs, rivers, permanent streams, natural ponds,

marshes or estuaries. All applications must include a 25 foot buffer vegetative strip within the buffer zone to decrease runoff.

DIMILIN® is a Registered Trademark of Chemtura Corporation, 199 Benson Road, Middlebury, CT 06749

All applicable directions, restrictions, and precautions on the registered product label for

Dimilin 21 (400-461) are to be followed.

These Use Directions must be in the possession of the user at the time of the pesticide application. 002
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Wyoming Adult Grasshopper Survey, 2008

This information is to be used by Land Managers and W&P Personnel in order to project possible outbreaks in spring of 2009.

State wide 1,646 stops were surveyed between 7/07/2008 and 9/4/2008.

Survey stops were collected by APHIS employees using the (18 sq. foot)/2 method.

All data was collected as point data and displayed using a fixed buffer.

Map Created by 

USDA APHIS PPQ WY

5353 Yellowstone Rd. Suite 208

Cheyenne WY 82009

Buffer Radius

Green 3.25 miles

Orange 3.00 miles

Red 2.50 miles

Blue 0.75 miles

Grasshopper Density

 # / Sq Yd

K 0

1 - 8

9 - 15

15 +

Crickets

GH per Sq. Yd. 9 to 15 15+ 9+ MC

Private 669,674 186,599 856,273 12,368

BLM 120,016 71,769 191,785 2,301

State Lands 74,777 18,968 93,745 2,162

USFS 21,962 2,086 24,048 805

Wind River Indian Reservation 0 788

Bureau of Reclamation 532 1,379 1,911

DOD

USFS, Grasslands 2,814 2,814

Bankhead Jones 3,624 3,624

National Park Service 5,084 3,090 8,174

Total Acres Infested 898,483 283,891 1,182,374 18,424

Acres
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Wyoming Adult Grasshopper Survey, 2009

This information is to be used by Land Managers and W&P Personnel in order to project possible outbreaks in spring of 2010.

State wide 1,631 stops were surveyed between 7/01/2009 and 9/3/2009.

Survey stops were collected by APHIS employees using the (18 sq. foot)/2 method.

All data was collected as point data and displayed using a fixed buffer.

Map Created by 

USDA APHIS PPQ WY

5353 Yellowstone Rd. Suite 208

Cheyenne WY 82009

Buffer Radius

Green 3.25 miles

Orange 3.00 miles

Red 2.50 miles

Blue 0.75 miles

Grasshopper Density

 # / Sq Yd

K 0

1 - 8

9 - 15

15 +

Crickets

GH per Sq. Yd. 9 to 15 15+ 9+ MC

Private 3,504,585 2,281,827 5,786,412 33,222

BLM 429,445 272,754 702,199 5,974

State Lands 412,519 228,773 641,292 4,857

USFS 62,649 26,134 88,783 2,719

Wind River Indian Reservation 7,816 16,201 24,017

Bureau of Reclamation 18,844 13,918 32,762

DOD 6,595 1,023 7,618

USFS, Grasslands 33,650 30,844 64,494

Bankhead Jones 65,556 35,124 100,680

National Park Service 18,279 1,573 19,852 2,261

Total Acres Infested 4,559,938 2,908,171 7,468,109 49,033

Acres