The Western battle with Mormon crickets dates back to the earliest days of European settlement.
During outbreaks, which occur seasonally during a several-year period, the flightless insects can cause everything from headaches for homeowners and drivers to substantial economic loss for ranchers and farmers.
This year, sludge from crushed crickets caused slick roadways in Eureka County, leading to multiple accidents. At Northeastern Nevada Regional Hospital in Elko, staff used leaf blowers, brooms and, at one point, even a tractor with a snowplow on it to push piles of crickets out of the way.
But the crickets, which are native to the Western United States, are considered a keystone species, meaning they fill specific roles that cannot be replicated by another species. Without them, their ecosystems would be drastically different, and they swarmed well before the expansive settlement of the West.
To control outbreaks, the United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) uses several forms of treatment, primarily relying on aerial spraying of pesticides. The main chemical used in the APHIS aerial spray program prevents juvenile insects from creating a new exoskeleton, causing them to die before they reach adulthood.
This year, 215,000 acres — roughly 336 square miles, or three times the size of Reno — were treated in Nevada.
But some groups are concerned about the far-reaching effects of the spraying, which can blow beyond the treated areas and harm other species — inhibiting growth and reproduction of freshwater invertebrates and killing larval honey bees.
A recent court decision on a lawsuit filed by those groups could have ramifications on how Mormon crickets, grasshoppers and other insects are managed across millions of acres in 17 Western states.
“Most invertebrates have relatively low mobility and can’t easily move out of harm’s way, especially the larval stages that are most vulnerable,” according to the Xerces Society, which is based in Portland, Ore., and over 500 miles away from northern Nevada.
In August, Oregon U.S. District Judge Marco A. Hernandez (nominated by Barack Obama in 2011), ruled on a lawsuit by the Xerces Society for Invertebrate Conservation and the Center for Biological Diversity against APHIS, ordering the agency to broaden its tools beyond relying on pesticides and to better assess and mitigate risk to other pollinators and rangeland insects.
The goal of the lawsuit was not to remove the use of pesticides altogether, said Sharon Selvaggio, pesticide reduction specialist at Portland's Xerces Society, but to spur consideration of other treatment methods, such as rotational grazing and limiting spraying to perimeters.
“APHIS seemed to have taken a step backward over the last 30 years and was just relying on pesticides,” Selvaggio said.
A spokesperson for the federal agency declined to discuss the lawsuit, stating in an email that “APHIS is currently reviewing the U.S. District Court’s decision and has no further comment.”
‘Some of the last great insect outbreaks’
Mormon crickets eat almost anything in their path — native perennials, grasses and shrubs; gardens and agricultural crops; even each other. Migrating in bands, they can travel as much as 1 mile per day and 25-50 miles per season, wreaking havoc along the way. In addition to damaging rangeland and crops, in large numbers, their feeding can contribute to soil erosion and poor water quality.
The outbreaks, often spurred by drought, can last as long as two decades.
As subdivisions, farms and other development encroach on Mormon cricket habitat, it creates conflicts between crickets and humans.
The most recent Mormon cricket outbreak in Nevada started in 2019.
“We recognize grasshoppers and Mormon crickets can be problems when they occur in high density, but viewing them as problematic is really short sighted,” said Selvaggio, who added that they serve as an important food source for other wildlife and as decomposers.
“When we think about the harsh environments in the Great Basin, the presence of a prey item in abundance like Mormon crickets is in some ways a small miracle for the birds, fish and mammals inhabiting these extreme environments,” she said.
The lawsuit’s decision will not pause the federal agency’s ability to spray, but it does force the agency to rethink its program strategies, Selvaggio said.
“The court has agreed pesticides shouldn’t be the first and only approach. The court is saying APHIS needs to think of efforts beyond pesticides when dealing with management,” Selvaggio said. “The program won’t shut down, but APHIS will kind of need to go back to the drawing board and figure out how to do this better for the future.”
The Nevada Department of Agriculture recommends areas for treatment when cricket populations average roughly two per square yard — nearly 1,300 per square mile. This year, the department received more than 900 calls, emails and texts about the insects.
Treatments must be approved by the U.S. Department of Agriculture; once approved, APHIS oversees the spraying. Areas can only be treated once per year — primarily due to environmental concerns, but also because of the short window the insects are active. Their life cycle lasts between just 60 and 90 days.
State entomologist Jeff Knight said the pesticides are not sprayed in condensed areas but rather over every second or third swath of land identified for treatment, in a stripe pattern.
His office has already begun preparing for next year’s cricket swarms, surveying more than 2,000 locations where crickets have laid eggs.
“We start sitting down, looking at it, so we can put the information together for … treatments,” he said. “Those aerial treatments take a lot of planning.”
In some areas surveyed, the crickets will never appear. In others, natural predators and parasites will kick in and drop the population back down, Knight said. And in others, there will be outbreaks.
Those who filed the lawsuit hope that, over time, the federal agency will broaden its toolbox beyond pesticides and find a way to mitigate effects on other species such as pollinators, dung beetles and aquatic insects, as well as the ecosystems Mormon crickets support, Selvaggio said.
“We need to find a balance that is sustainable for the long run,” she said.
Outbreaks will remain a nuisance for some people, but Kevin Burls, conservation biologist with the Xerces Society in Portland, Ore., said he hopes some people will be able to appreciate the infestations for what they are — some of the last great insect outbreaks on the planet.
“It’s strange, but that strangeness is also very unique and amazing,” Burls said.