Federal organization sued over rangeland pesticide use
Two environmental groups are suing the Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) for its use of pesticides to control outbreaks of grasshoppers and mormon crickets in western states.
The lawsuit filed in an Oregon District Court by the Xerces Society and Center for Biological Diversity claims APHIS has ignored its congressional mandate for a ‘holistic’ approach to grasshopper control and instead focused almost solely on the use of pesticides.
Drought can exacerbate grasshopper population growth because natural fungi poisonous to the insects don’t develop as well in dry conditions.
Left alone, grasshoppers could decimate rangeland food for non-native livestock, and can also have detrimental effects on crops like barley and wheat. More than 400 species of grasshoppers exist in western rangeland but only a dozen are considered pests, according to APHIS.
The agency monitors grasshoppers in 17 western states, and when it deems there’s an outbreak or is asked to intervene by stakeholders like the US Forest Service or adjacent land owners, it can apply a pesticide to kill the insects.
“It prevents the insect from molting, and you end up with insects that basically die,” explains Michael Perrella, an entomologist and Dean of the College of Agricultural and Life Sciences at the University of Idaho.
APHIS documentation shows it primarily uses a chemical called diflubenzuron to accomplish grasshopper control. Parrella said it’s an effective product used for decades, without specific harmful effects to mammals or fully developed insects.
But, he said, “there's sort of a risk you're taking any time you make a pesticide spray; you have to balance the risk with the potential benefit.”
Parrella isn’t intimately familiar with the APHIS grasshopper control program but said he would assume the agency has done its due diligence. He cited a large amount of data from decades of diflubenzuron use on the east coast to treat gypsy moth infestations.
The lawsuit contends APHIS hasn’t checked all the boxes since re-authorizing its rangeland pesticides program in 2019.
“The environmental impact statement (“EIS”) prepared pursuant to the National Environmental Policy Act (“NEPA”) does not even disclose the locations of past pesticide applications. Nor does the 2019 EIS make any meaningful attempt to consider how APHIS’s program combines with actions taken by other actors—private, state, tribal, and federal—to affect native pollinators, other invertebrates, or animals and plants that depend on these invertebrates for food or pollination,” the lawsuit reads.
APHIS reports it directly treated more than 800,000 acres of rangeland for grasshoppers in 2021, in Mountain West states from Montana to New Mexico. The application process treats alternating swaths of land, meaning the total treated area is considered to be 1.6 million acres.
A heat map of grasshopper density shows the insects were most populous last year in eastern Oregon and Montana.
Parrella said when applied properly, chemicals targeting invertebrates during molting don’t affect fully developed insects. Dimilin is the commercial name for the pesticide diflubenzuron.
“But, there's the concern that maybe pollinators would pick up residue from dimilin, bring it back to either the hive or where they're rearing young,” he said.
Advocates say eliminating grasshoppers also harms a key food source for native rangeland birds and protected species like sage grouse.
“APHIS is out of control, spraying deadly poisons on biodiversity hotspots like Oregon’s Malheur National Wildlife Refuge, which is visited by tens of thousands of people each year eager to see the incredible diversity of birds and wildlife there,” said Lori Ann Burd, environmental health director at the Center for Biological Diversity in a press release. “It’s time for this outlaw arm of the USDA to be held accountable for actively contributing to the escalating extinction crisis.”
Parrella does not think any treatment could accomplish its goals without side effects of some type, but he said there are biological alternatives to dimilin.
The lawsuit alleges the environmental impact statement the rangeland pesticide program operates under is incomplete and violates environmental protection laws.
A spokesperson for APHIS said the agency would not comment on pending litigation.