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For Immediate Release, May 24, 2022


Sharon Selvaggio, Xerces Society for Invertebrate Conservation, (503) 704-0327, [email protected]

Scott Hoffman Black, Xerces Society for Invertebrate Conservation, (503) 449-3792, [email protected]

Andrew Missel, Advocates for the West, (503) 914-6388, [email protected]

Lori Ann Burd, Center for Biological Diversity, (971) 717-6405, [email protected]

WASHINGTON: Tuesday, May 24, 2022 — The Xerces Society and Center for Biological Diversity filed a notice of intent today to sue the U.S. Department of Agriculture’s secretive Animal and Plant Health Inspection Service for failing to properly consider harms to endangered species caused by insecticide spraying across millions of acres of western grasslands.

APHIS oversees and funds the application of insecticides on rangelands in 17 states to prevent native grasshoppers from competing with livestock for forage.  

The main insecticide sprayed is diflubenzuron, which kills insects in their immature stages. It is typically sprayed from airplanes over areas of at least 10,000 acres. Studies have shown the insecticide reduces populations of bees, butterflies, beetles, and a wide variety of other insects. Aquatic invertebrates consumed by endangered fish and trout are also vulnerable.

Grassland ecosystems are home to many endangered and threatened species, including flowering plants, mollusks and many different mammals. Additionally, several once-common species on rangelands, including greater sage-grouse, monarch butterfly, and the Western bumble bee, are in steep decline and are the focus of conservation efforts, including possible listing under the Endangered Species Act. Many protected species depend directly on insects for their food or for pollination. 

“Xerces doesn’t enter into lawsuits lightly, but in this case the risks are too great,” said Scott Black, executive director at the Xerces Society. “Over 80% of animals in grasslands are insects. When these are harmed by insecticide sprays, it could cause a cascade effect to the many endangered grassland species that rely on insects to survive."

Endangered species like yellow-billed cuckoos, black-footed ferrets, bull trout, Ute ladies’-tresses orchids, Oregon spotted frogs and Spalding’s catchflies are present in multiple states in which the insecticide spraying program operates. But APHIS has failed to properly consider how the widespread insecticide use may harm these species across their range, as required under the Endangered Species Act.

“The last time APHIS completed a programmatic look at how its rangeland pesticides program affects endangered insects, birds and plants, Bill Clinton was in his first term as president, Friends was in its second season and Google did not yet exist,” said Andrew Missel, staff attorney at Advocates for the West, who is representing the conservation groups. “It’s way past time for APHIS to take a fresh look at how dousing hundreds of thousands of acres across the West with pesticides impacts the species that need the most protection.”

Other insecticides approved for use in the spraying program include highly toxic carbaryl and malathion and a newer insecticide, chlorantraniliprole. The Environmental Protection Agency has determined that carbaryl is likely to harm 1,640 listed species, or 91% of all endangered plants and animals and malathion is likely to harm 1835 listed species, or 97% of all endangered plants and animals. Chlorantraniliprole is a systemic pesticide, meaning it is absorbed by plants’ leaves, pollen and nectar, exposing bees and butterflies for an extended time. Studies show it is highly toxic to monarch butterfly and other caterpillars.

“It’s outrageous that amid our heartbreaking extinction crisis, APHIS continues to give itself carte blanche to spray incredibly toxic poisons on millions of acres of wildlife habitat throughout the West,” said Lori Ann Burd, director of environmental health at the Center for Biological Diversity. “They’ve made a habit of refusing to follow the law and now we’re going to hold them accountable.”

The states in which the insecticide spraying is approved include Arizona, California, Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington and Wyoming. 

Federal agencies are required to consult with the U.S. Fish and Wildlife Service when they undertake projects that may affect listed species, yet APHIS and the Service have not completed programmatic consultation for grassland insecticides program for 27 years. Since then, many species potentially affected by the program have been listed as endangered, including bull trout, northern Idaho ground squirrels, northern long-eared bats, Preble’s meadow jumping mice and Oregon spotted frogs.

Beyond impacts to federally listed species, APHIS’s program poses larger risks to grassland ecosystems. Insects are a critical, often overlooked, part of a functioning planet and society. Most birds, freshwater fish and mammals consume insects as food. People and wildlife also depend on insect pollination for fruits, vegetables, nuts and seeds. These ecological contributions generate significant monetary value; one study found that insects contribute more than $70 billion per year to the U.S. economy. 

The public supports protection for wildlife and is especially concerned with the welfare of pollinators, which are negatively affected by these spray programs. Eighty percent of western voters agree that loss of pollinators is a serious problem, according to a 2020 Colorado College poll. This concern held true in every state and across all types of communities: cities (85%), suburbs (81%), small towns (77%), and rural areas (76%).



The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.

The Xerces Society is a nonprofit organization that protects the natural world by conserving invertebrates and their habitat. Established in 1971, the Society is a trusted source for science-based information and advice and plays a leading role in promoting the conservation of pollinators and many other invertebrates. 

Advocates for the West is a public interest, nonprofit environmental law firm that protects and defends winning for the West’s public lands, waters, fish natural treasures and wildlife.


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Description: A western bumble bee (Bombus occidentalis) forages on an aster flower. Prior to 1998, the western bumble bee was both common and widespread throughout the western United States and western Canada, but populations have since declined sharply.

Photo credit: Rich Hatfield, Xerces Society

File name: B_occidentalis_RichHatfield_XercesSociety