Western drought brings another woe: voracious grasshoppers
A drought blanketing the U.S. West is drying up waterways, sparking wildfires and leaving famers scrambling for water
June 24, 2021, 3:29 AM
5 min read
Share to FacebookShare to TwitterEmail this articleThis undated photo provided by the U.S. Department of Agriculture's Animal and Plant Health Inspection Service shows a male migratory grasshopper. Besides feeding on grasslands, large grasshopper populations can also devastate cultivated crops such as alfalfa, wheat, barley, and corn. (U.S. Department of Agriculture's Animal and Plant Health Inspection Service via AP)
BILLINGS, Mont. -- A punishing drought in the U.S. West is drying up waterways, sparking wildfires and leaving farmers scrambling for water. Next up: a plague of voracious grasshoppers.
Federal agriculture officials are launching what could become their largest grasshopper-killing campaign since the 1980s amid an outbreak of the drought-loving insects that cattle ranchers fear will strip bare public and private rangelands.
In central Montana's Phillips County, more than 50 miles (80 kilometers) from the nearest town, Frank Wiederrick said large numbers of grasshoppers started showing up on prairie surrounding his ranch in recent days. Already they're beginning to denude trees around his house.
“They're everywhere," Wiederrick said. “Drought and grasshoppers go together and they are cleaning us out."
Grasshoppers thrive in warm, dry weather, and populations already were up last year, setting the stage for an even bigger outbreak in 2021. Such outbreaks could become more common as climate change shifts rainfall patterns, scientists said.
To blunt the grasshoppers' economic damage, the U.S. Department of Agriculture this week began aerial spraying of the pesticide diflubenzuron to kill grasshopper nymphs before they develop into adults. Approximately 3,000 square miles (7,700 square kilometers) in Montana are expected to be sprayed, roughly twice the size of Rhode Island.
Agriculture officials had seen this year’s infestation coming, after a 2020 survey found dense concentrations of adult grasshoppers across about 55,000 square miles (141 ,000 square kilometers) in the West. A 2021 grasshopper “hazard map” shows densities of at least 15 insects per square yard (meter) in large areas of Montana, Wyoming and Oregon and portions of Idaho, Arizona, Colorado and Nebraska.
Left unaddressed, federal officials said the agricultural damage from grasshoppers could become so severe it could drive up beef and crop prices.
The program's scale has alarmed environmentalists who say widespread spraying will kill numerous insects, including spiders and other grasshopper predators as well as struggling species such as monarch butterflies. They're also concerned the pesticides could ruin organic farms adjacent to spray zones.
“We’re talking about natural areas being sprayed, this is not cropland,” said Sharon Selvaggio, a former U.S. Fish and Wildlife Service biologist now with the Xerces Society, a conservation group focused on insects.
Government officials say they will spray pesticides in low concentrations and reduce the area treated by alternately spraying a strip of rangeland, then skipping the next strip. The intent is to kill grasshoppers passing between strips while sparing other insects that don't move as far.
If spraying is delayed and grasshoppers grow larger and more resilient, federal officials could resort to two more toxic pesticides — carbaryl and malathion, according to government documents.
Selvaggio said pesticides could drift into areas not being targeted and kill beneficial insects such as bees that pollinate crops. “The toxicity is more than enough to kill bees," she said. “This is not adequate protection."
Organic farmers are divided on spraying. Some are concerned about losing their organic certification for years if they inadvertently get pesticides on their crops, while others are willing to tolerate spraying out of deference to their neighbors' problems, said Jamie Ryan Lockman, director of Organic Montana.
The trade group isn't going to challenge the spraying but wants organic farmers protected and for the government to research alternatives to chemicals for future outbreaks.
