The plight of the monarch butterfly could cost farmers a valuable tool in the fight to protect crops from weeds and pests.
An effort is underway to list the monarch butterfly as threatened under the Endangered Species Act. If the move comes to fruition, it could potentially limit where farmers can apply herbicides and pesticides, heightening the risk of crop losses.
The root of the issue isn’t necessarily the monarch itself, but rather a plant that is vital to its life cycle, yet a damaging weed to crops.
According to the proposal by the U.S. Fish and Wildlife Service to list the monarch butterfly as threatened, if enacted, there would be an emphasis on protecting critical habitat. Since the species relies heavily on milkweed during its life cycle, there has been concern from the agriculture sector about potential limits to control the weed in fields with herbicide, along with the use of pesticides.
“There was a lot of speculation the Fish and Wildlife Service was going to restrict herbicide use,” said Brigit Rollins, a staff attorney with the National Agricultural Law Center. “I’m not going to rule that out, but they are specifically highlighting insecticide.”
Any restriction resulting from the proposal could be costly.
According to Penn State, farmers in the U.S. spend more than $11 billion per year on herbicides to control weeds such as milkweed. The U.S. Department of Agriculture estimates that in 2021 reduced crop yields from weeds cost $33 billion, making weed management a bigger financial burden than insect and disease control combined.
While the proposed rule to list the monarch has exemptions in place regarding removing or controlling milkweed, there is a caveat.
According to Rollins’ interpretation of the rule, if maintaining, enhancing or removing established milkweed results in conversion of native or naturalized grassland, it would be considered harmful to the monarch.
“I think for ag in particular, that’s going to be really important,” she said. “It opens some questions of what is going to be considered conversion of native or naturalized grassland.
“How would that impact folks who are part of a conservation program with USDA, that put some land aside that’s now become grassland but they intend to convert it back to cropland later on?”
One program alluded to by Rollins is the Conservation Reserve Enhancement Program, which pays farmers on a per-acre basis to take land out of production. The program is contractual and terms extend for 10 or 15 years. At the end of the obligation, the land can be reverted back into crop production, and that’s where the definition of naturalized grassland and the monarch comes into question.
In Pennsylvania, more than 82,000 acres have been enrolled in CREP as of December 2023 and the state has set of goal of enrolling 265,000 acres. A similar program authorized by the USDA, the Conservation Reserve Program, accounted for 22.9 million acres nationally at the end of 2023.
Other agricultural activities that would be exempt from being considered “take” under the proposed rule include grazing, vegetation and invasive species management, construction and maintenance of fences, and watering areas.
“If you are removing milkweed, if you’re removing nectar plants, as long as monarchs aren’t present, that really should not be of concern,” Rollins said.
“That’s not going to be a violation of the (Endangered Species Act).”
There was also concern that protection of critical habitat areas — which could include milkweed — would be very broad under the proposed rule for the monarch.
Critical habitat is those areas that if destroyed or significantly degraded could result in a species going extinct.
However, the critical habitat designation under the monarch proposal isn’t broad, Rollins said, and mainly focuses on overwintering areas as opposed to breeding and migratory locations.
The eastern population of the monarch overwinters in Mexico, and the western population overwinters along the California coast.
“We’re not seeing any critical habitat being proposed for the eastern population,” she said.
But Rollins said questions still remain on how the proposed rule could impact pesticide use, and she felt the Fish and Wildlife Service is still considering how it should address pesticide impacts to the monarch, if it even should be addressed at all.
According to Rollins, the agency is considering allowing the Environmental Protection Agency’s new policy to be the “guiding light” for reducing pesticide impacts on listed species.
She added the proposed rule to list the monarch was put out during the Biden administration, but it’s unclear what the Trump administration will do with the proposal. Options include issuing a final listing after public comment, rescinding the proposal or doing nothing.
“I do think that if they rescinded the proposal or kind of gave some indication that they were really just sitting on the proposal and not necessarily looking to draft a final rule, I do think it’s very likely we would see a lawsuit come out of that,” Rollins said.
