BLM decides on insecticide spraying to treat possible grasshopper outbreak on lands in Wyoming

BLM decides on spraying strategy for grasshoppers

CHEYENNE, Wyo. — If Wyoming experiences a grasshopper outbreak this summer, pest control officials will treat U.S. Bureau of Land Management property in the state by spraying swaths of land with insecticide.

The BLM conducted an environmental study of methods to suppress the bugs and recently selected the “Reduced Area and Agent Treatment” method, known as RAATs. The plan, a common method of treating grasshopper infestations, involves spraying alternating strips of land with the insecticide diflubenzuron, which stops grasshoppers from growing.

Treating intermittent strips is more efficient than blanket spraying and is still effective because grasshoppers are exposed to the poison as they move in and out of the treated strips, pest control officials say.

The BLM decided against a similar alternative that would have required more restrictive buffers around certain bird and big game habitat.

The agency is taking feedback on its environmental study through Monday, but has already found that its preferred treatment would have no significant environmental effects, said Ken Henke, Wyoming BLM’s weed and pest coordinator.

The 10 local BLM field offices in Wyoming will have a chance to place tighter restrictions on spraying if they wish, he said.

“If public comments come in, if there’s something really significant we missed or some issue we just overlooked, that also could be addressed in the final (environmental assessment),” Henke said.

A federal survey of adult grasshoppers last fall indicated that northeast and north-central Wyoming could become infested with grasshoppers this summer. The insects are native to Wyoming, but outbreaks of certain pest species can be problematic because of their voracious appetites for grass.

Pest control officials consider outbreak levels to be about 15 grasshoppers per square yard — enough to cause economic problems.

The BLM, which manages more than 28,100 square miles of federal land in Wyoming, doesn’t actually treat any of its land. Its treatment decision would apply to spraying BLM land by county weed and pest districts and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.

The BLM expects to spend an estimated $800,000 to $900,000 this summer to pay for its share of county weed and pest district spraying efforts, Henke said.

Suppressing grasshoppers is important to protect forage for livestock and to protect rangeland for wildlife species that depend on it for food or winter cover.

“Our lands on the east side of the state are intermixed with private lands, and so being good neighbors to landowners, we have some responsibility to look at cropland protection as well,” Henke said.

The BLM’s preferred treatment also calls for using other pesticides for site-specific treatment of grasshoppers that have reached adulthood. The plan also contains spraying restrictions to protect water bodies, sage grouse leks, bees, the Wyoming toad, the Kendall warm springs dace fish, the blowout penstemon plant, the Colorado butterfuly plant, the Ute ladies’ tresses plant, the desert yellowhead plant.