Grasshoppers in the Whitetall Mountains in the Butte Ranger District of Beaverhead-Deerlodge National Forest Montana, September 13, 2019. USDA Photo by Preston Keres

As the West is amid a megadrought, farmers and ranchers are reporting another problem: grasshoppers.

USDA’s 2021 Rangeland Grasshopper Hazard Map shows densities of at least 15 insects per square yard in large areas of Montana, Wyoming and Oregon, and portions of Idaho, Arizona, Colorado and Nebraska.

According to the Associated Press (AP), federal officials are launching an aerial grasshopper-killing campaign by spraying the pesticide diflubenzuron, beginning with 3,000 square miles in Montana to kill grasshopper nymphs before they develop into adults. Grasshoppers reproduce and lay eggs in the fall, and agriculture officials saw this year’s infestation coming after a 2020 survey found dense concentrations of adult grasshoppers across about 55,000-square miles.

Without the aerial spraying program, agricultural officials state damage could be so severe it could drive up prices of crops and beef. According to a study from the University of Wyoming cited by federal officials, the average grasshopper infestation can destroy 20 percent of crops, causing up to $900 million in damages.

“They are competing against our food supplies,” said Marko Manoukian, a Montana State University Agriculture Extension agent in Phillips County.

Environmental groups are concerned about the scale of the project, stating in addition to grasshoppers, it would harm beneficial insects and species in peril, such as the monarch butterfly. They also contend the spraying could harm organic farms adjacent to the spray zones.

Sharon Selvaggio, a former U.S. Fish and Wildlife Service biologist with the Xerces Society, stated, “the toxicity is more than enough to kill bees.”

“This is not adequate protection,” he said after learning the spraying will be in low concentrations and alternate strips of rangeland would be sprayed.

“This year’s outbreak will peak in roughly two months, when the insects reach 2 to 3 inches in length and become so prevalent, they’ll start to eat more plant matter than cattle can,” Chelse Prather, a University of Dayton insect ecologist, told AP.

According to researchers, the last outbreak on a scale comparable to this year lasted from 1986 to 1988, when almost 20 million acres were treated with malathion. — Charles Wallace, WLJ editor

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