WASHINGTON, D.C. – A lawsuit against the Environmental Protection Agency could force the agency to conduct an immediate review of the widely used herbicide glyphosate and its effects on monarch butterflies (Natural Res. Def. Council v. EPA, S.D.N.Y., 1:15-cv-01462, 2/27/15).

The lawsuit, filed Feb. 27 by the Natural Resources Defense Council, asks the U.S. District Court for the Southern District of New York to require the EPA to respond to a 2014 petition asking the agency to review glyphosate.

The petition argued glyphosate is having a devastating effect on North American monarch butterflies because overuse of the herbicide has decimated the milkweed plants that the monarch’s larvae rely on as their sole food source. “This winter, only about 56.5 million butterflies—the second lowest number ever measured—reached their winter refuge,” the council said in its lawsuit. “The remaining population is so small that a single severe weather event could eradicate it.”

Late last year, the U.S. Fish and Wildlife Service initiated a process to determine whether it should place the monarch butterfly on its endangered species list (39 CRR 12, 1/5/15).

If the NRDC’s lawsuit is successful, the EPA would have 30 days to respond to the glyphosate petition and six months to complete its review.

A copy of the NRDC’s complaint is available here.