Risk Management Approach to Identifying Options for Protecting the Monarch 

Butterfly

The Environmental Protection Agency (EPA) is concerned about the dwindling population of 

monarch butterflies and intends to identify efforts that will protect the monarch butterfly by

conserving the milkweed plant, the plant upon which monarch butterfly larvae depend. In this 

document, the EPA’s Office of Pesticide Program outlines an approach for taking action to 

protect monarch butterflies. This document is the start of the process which will depend upon (i) 

input from a diverse group of stakeholders to identify and integrate information with respect to 

influences on the population dynamics of the monarch butterfly and the milkweed plant; and, (ii)

cooperation and collaboration from these diverse stakeholders to identify activities that will 

balance weed management needs across varied landscapes with conservation of the milkweed

plant.

Background 

Over the past decade, threats to pollinators, including honey bees, bats, and butterflies, have

become an important issue. Pollinators play a key role in agriculture and food production, and 

thus the issue of declining pollinator health has been the focus of much research and work. Over 

the past several years, the EPA has been working with a wide range of partners to develop 

measures to protect pollinators from the potential effects of pesticides. As EPA continues its 

pollinator protection efforts, it is expanding its pesticide risk management efforts to include steps 

to protect monarch butterflies.

The EPA is initiating efforts focused specifically on the monarch butterfly for several reasons. 

First, the U.S. has been engaged in an effort with Canada and Mexico through the 

Canada/Mexico/U.S. Trilateral Committee for Wildlife and Ecosystem Conservation and 

Management, where the three partner nations have agreed to make natural resource conservation 

a priority. Consistent with its objective to conserve and manage natural resources across North 

America, the committee has recognized the monarch butterfly as an emblematic species shared 

by the three countries and renewed their collaborative effort to protect the species and its 

required resources. Secondly, in addition to the efforts of the Trilateral Committee, President

Obama issued a memorandum on pollinator protection entitled, Creating a Federal Strategy to 

Promote the Health of Honey Bees and other Pollinators. The memorandum highlights the 

importance of the monarch butterfly and establishes a task force of Federal agencies to develop a 

strategy to conserve pollinators and the monarch butterfly in particular. The memorandum states 

that the task force is to develop a strategy that looks to developing partnerships with external 

stakeholders such as state, tribal and local governments, farmers, corporations, and nongovernmental organizations to achieve the goal of protecting and conserving the monarch

butterfly and its habitat. Finally, in February 2014, the EPA’s Office of Pesticide Programs 

(OPP) received a petition from the Natural Resources Defense Council (NRDC) asking the EPA 

to take actions to reduce the use of the herbicide, glyphosate, because NRDC believes that the

widespread use of glyphosate has impacted the monarch butterfly by reducing the presence of the 

milkweed. While the EPA has denied NRDC’s petition, the EPA concludes that its ongoing 
efforts to protect bees, in conjunction now with this effort to protect the monarch butterfly, are in 

line with the objectives of the NRDC petition.

Numerous publications have highlighted the importance of the common milkweed (Asclepias 

syriaca L.) as a critical food resource for monarch butterfly larvae (Danaus plexippus L.), and 

have emphasized the importance of conservation of milkweed to preserve monarch butterfly

populations. In addition, together with several non-governmental organizations, various 

agencies within the Federal government have been working collaboratively with the Monarch 

Joint Venture1to develop and implement measures to protect monarch butterflies and their 

migration. In this document, EPA identifies the types of information that may be important to 

have in order to identify appropriate actions to take under the Federal Insecticide, Fungicide, and 

Rodenticide Act (FIFRA) to protect monarch butterflies (including milkweed resources) while 

also enabling pesticide users to meet important weed management needs. The approach and 

objectives outlined here will support and complement the actions and objectives of the Trilateral 

Committee and the Presidential Memorandum on Pollinator Health.

Outreach

In its efforts to conserve and protect the monarch butterfly and the milkweed plant, the EPA 

anticipates working with a range of partners to identify information, develop and implement 

actions, and track progress on reducing risk to the species. Since threats to pollinators, including 

the monarch butterfly and its resources, are many, efforts to protect such resources will need to 

be multifaceted and reflect the interests of various sectors such as federal, academic, public, 

industry, and non-governmental. EPA’s efforts therefore, will be informed and built upon input 

from these stakeholders. We will look to our stakeholders to provide input for developing

actions that are meaningful and are aimed at the protection of the monarch butterfly and its 

habitat but that are also balanced with respect to land owners needs for weed and vegetation 

management. 

In a similar manner, efforts of the EPA and its stakeholders will be further coordinated and part 

of broader efforts that will be led by the U.S. Department of the Interior (DOI). DOI has the lead 

among the federal agencies assigned to develop a strategy to conserve the monarch butterfly. 

Efforts led by the DOI will likely address other factors and issues (other than herbicides) that are 

affecting the monarch butterfly and its critical resources. Ultimately, the broad and multifaceted 

strategies of the U.S. will be coordinated with our North American partners – Mexico and 

Canada – not only so ideas and approaches can be shared, but to insure that efforts between the 

countries are complementary.

Objective and Scope

The EPA will contribute to ongoing monarch butterfly conservation efforts by identifying 

situations in which areas of milkweed can be preserved in a manner that balances this objective 

 

1 Additional information about the Monarch Joint Venture, its mission, and Federal partners can be found at: 

http://www.monarchjointventure.org/.
with weed management needs. The EPA will seek to identify these situations for areas that are 

important to the monarch butterfly. The EPA envisions working with a range of stakeholders 

such as pesticide users from both the agricultural and non-agricultural community; members 

from the academic community including extension personnel; representatives from nongovernmental organizations; state agencies, and the public. Interactions with these stakeholders

will identify opportunities to reduce the potential impact of herbicides on the milkweed plant. 

The Agency with input from stakeholders will review both direct effects, which are those that 

occur at or very close to the time of the pesticide application itself; and, indirect effects, which 

occur by or as a result from the pesticide and are later in time, but still reasonably certain to 

occur. For example, direct effects to the monarch butterfly, from herbicides, insecticides or other 

types of pesticides can be addressed through the agency’s risk assessment framework utilized for 

estimating effects to other pollinators. And so, the focus of this effort will be on reducing 

potential indirect effects to the monarch butterfly from herbicide impact on milkweed plants. 

The EPA also recognizes that it is possible that if EPA were to take regulatory action to reduce 

the potential impact from one herbicide to protect important monarch butterfly resources, such 

efforts could result in a market shift to other herbicides that would not be subject to similar risk 

mitigation measures. To the extent that happened, there could well be little or no improvement 

for monarch butterflies. In order to avoid this, the EPA envisions that its effort should not be 

limited to looking at just one or two herbicides, but across a number of herbicides. To begin to 

determine which herbicides ought to be considered in the scope of this action, the EPA will 

consider and evaluate different types of information such as: 

(i) volume of use of various herbicides on acreage in agricultural production and in nonagricultural areas such as rights-of-way, pastures/rangeland, forestry sites, and 

industrial areas critical to the monarch butterfly and where the milkweed plant is 

commonly found; 

(ii) information on the monarch butterfly such as its lifecycle, seasonal distribution, its 

population demographics over time, and any modeling analyses relevant to critical 

life stage parameters to which the monarch butterfly population is most sensitive;

(iii) availability of laboratory or field data that specifically relates to the effects of various 

herbicides on the milkweed plant species; 

(iv) information on both spatial and temporal parameters of weed management needs 

particularly with respect to different land use categories and herbicide uses; and in 

agricultural production areas where herbicide use may overlap with habitat of the 

monarch butterfly development, reproduction, and migration; and

(v) information on existing practices that promote co-occurrence of agricultural 

production with maintenance of milkweed populations.

Balance of Weed Management and Milkweed Protection

The EPA understands that efforts to reduce the impact of herbicides on milkweed must take into 

account the weed management needs of the sites being treated. In certain scenarios, such as crop 

production, milkweed plants in an agricultural field are considered weeds, and their presence 

may be incompatible with other goals of these land uses. In other scenarios, such as nonagricultural, industrial, or rights-of-way, milkweed may not be a target species of herbicide use. 

In these scenarios, herbicides are employed as part of integrated vegetation management to 
selectively eliminate or control certain plant species. Use of herbicides in this context can result 

in more stable plant communities (such as those composed of native species) that contributes to 

supporting wildlife and wildlife habitat by reducing fragmentation or threats from soil erosion or 

wildfire.

Information on weed management across the variety of landscapes where milkweed can be found 

and the impacts of not controlling it or other weedy species will be crucial to developing options 

to conserve monarch butterfly habitat. This is particularly important in non-crop areas, where 

herbicide use may overlap with the habitat of monarch butterfly development, reproduction, and 

migration. Such information will help the EPA to identify opportunities to balance milkweed 

protection while still meeting weed management needs across the varied landscapes where it can 

be found.

Analysis and Actions

The efforts to conserve the milkweed plant from effects of herbicides may encompass a number 

of pesticidal compounds. Therefore, in contrast to a typical quantitative single-chemical analysis 

approach, the EPA will rely upon both qualitative and quantitative analyses to weigh risks and 

benefits and identify actions to conserve the milkweed plant where it is important to monarch 

butterflies. The EPA anticipates that a number of actions could be taken to protect monarch 

butterflies – for example, requiring changes to pesticide label instructions such as: lowering the 

rates, decreasing the frequency; modifying the timing of applications; or establishing spray drift 

buffers in fields that are treated with pesticides in order to protect critical milkweed resources. 

The agency could also support education and training on best management practices. These 

management practices may be in addition to and complementary of other conservation efforts 

aimed at creating, conserving, or restoring wildlife habitat. Interaction between partners of 

different sectors to adopt management practices in a coordinated manner not only at the field 

level, but at the landscape level and area-wide level as well, will be important for success. For 

example, conservation banking effort(s) could be undertaken that could establish, preserve, or 

restore habitat for monarch butterflies, or cooperative efforts could be established to fund further 

research into protection measures for the monarch butterfly. If appropriate, support of such 

efforts could be considered by EPA as risk mitigation in regulatory decisions for herbicides that 

are determined to adversely impact the monarch butterfly. The agency is soliciting public 

comment on which potential action or a combination of actions discussed above would be the 

most effective in reducing the impacts of herbicides on the monarch butterfly. The agency is also 

requesting that any additional measures not discussed here be identified.

Next Steps

Following the 30-day comment period, EPA will evaluate any comments or information 

submitted in response to its proposed approach for protecting monarch butterflies. EPA will 

begin to gather and assess information to understand weed management needs as well as 

information on the monarch butterfly and milkweed. In the near future EPA will reach out to 

engage stakeholders to develop potential steps forward. EPA is also continuing to work with the 

coalition of government agencies in response to the Presidential Memorandum, in which efforts 

regarding the monarch butterfly are being led by the DOI. EPA believes that open 
communication with the full range of stakeholders engaged on this issue will be important in 

order to identify and coordinate actions that can be taken to protect monarch butterfly and its 

resources in a manner that also considers weed and vegetation management needs in the varied 

landscapes where herbicides are used.