Grasshopper infestation continues after pesticide spray canceled

The pasture on Gerald Chacon’s ranch looks like it has been mowed too close, he said, with bare patches of ground showing.

Grasshoppers stripped the soil, Chacon said. For about a year, the Rio Arriba County Extension Office has been working with landowners to find a solution for the insects, which have been devouring rangelands west of Cebolla.

“The grasshoppers last year … I mean, it was really devastating,” Chacon said. “And it’s about to happen again.”

In November 2022, a group of ranchers asked for federal help dealing with the infestation, and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service planned a controversial spray to limit the grasshopper populations.

The plan received significant pushback from environmentalists and tribal groups, and was ultimately canceled last month.

On June 29, the Bureau of Land Management announced it would be halting the spray, after reviewing APHIS’s environmental assessment of the plan and determining that additional outreach and environmental analysis were required before making any decisions.

Now, according to an APHIS spokesperson, it’s up to landowners and managers such as Chacon to decide on treatments for the pest, at least this year.

But some ranchers say it might already be too late, as grasshoppers start laying eggs for next year.

‘Ride it out’

Linda Hutchison, who has ranched in the area for 27 years, said she’s not planning to take any action. She’s not certified or comfortable using a heavy insecticide — and even if she sprayed her own pastures, if her neighbors are still infested it wouldn’t matter, she said.

“For me, it’s too late,” Hutchison said. “Your options to be able to control it are much, much less.”

A spokesperson for BLM said the agency will be conducting its own environmental analysis and plan to be ready for winter or spring pest control options. The spokesperson said the office had received over 500 calls about concerns of chemical pesticide use, and about a dozen from ranchers and farmers worried about the impact on their crops.

Donald Martinez, county program manager and agricultural agent for the County Extension Office, said the infestation is an ongoing situation. The office has received an influx of calls from impacted landowners, Martinez said.

“They’re getting beat up pretty bad,” Martinez said.

Given the cancellation, Martinez said the county may need to “ride it out” until next season.

Spoiling the soil

Chacon’s family has been raising cattle for seven generations. He’s been moving his cattle to other land allotments in the forest less affected by grasshoppers, at high cost.

“We have no choice but to move the cows out when we run out of grass,” Chacon said.

Besides the cost of trucking, his cattle have experienced weight loss, and six calves have been lost to bear attacks as they traveled through the forest.

Many people raised concerns about unintended environmental effects if the spray went forward.

But Chacon said that leaving the grasshoppers untreated can also damage the environment. The insects strip the soil, Chacon said, making it vulnerable to erosion in periods of high wind or heavy rains. When the grass is eaten, it recovers slower, Chacon said.

Charles Hibner, a retired soil scientist and rancher in the region, said his main priority is protecting the soil. When the topsoil, which has the most organic material, is lost, Hibner said, it can make it difficult for plants to root and grow.

Hutchison said she’s already lost one pasture, making what she calls “stewardship” efforts more difficult in the region. She rotates her 25 head of cattle between five pastures to prevent overgrazing. Losing one pasture makes that harder.

Grasshoppers also compete with other animals that eat grass and vegetation, such as elk and deer, which can impact the predators that feed on them.

“It all piles up on you,” Chacon said. “Not just on us, but on wildlife as well.”

Why so many?

There are almost 400 grasshopper species in the Western United States, said a spokesperson for APHIS in an email to the Journal. But just 12 species are considered pests.

Grasshoppers and Mormon crickets are native to the rangeland ecosystem. But, when those populations reach outbreak levels, they can cause “serious economic and environmental losses,” the spokesperson said.

Almost all of the species identified this year were Auocara elliotii or Melanoplus occidentallis — two grasshopper species that can be incredibly damaging in high levels, the spokesperson said.

New Mexico isn’t the only state being affected by grasshopper infestations. Scott Bundy, professor of entomology at New Mexico State University, said Nevada and Colorado have also been hit hard this year.

Bundy said it can be difficult to predict what years will prove grasshopper-happy. Environmental conditions are one factor that’s trackable, Bundy said — generally, in a wet year, when vegetation is plentiful, grasshoppers will proliferate and lay many eggs. But if those eggs hatch during a dry spell, swarms of grasshoppers will go on the move to find whatever vegetation they can.

That may have been what happened in 2014, when a cloud of grasshoppers in Albuquerque grew so big that it became visible on National Weather Service Radars.

And it may be a factor now, as the state sees hot, dry weather following a wetter fall, exacerbating a boom in grasshopper populations.

“Probably what happened last year was nice conditions, lots of insects — then this year, those babies come out, and they’re looking for food,” Bundy said. “In order to find it, then they started moving.”

Management options

According to Bundy, both Mormon crickets and grasshoppers can be beneficial to an ecosystem — in moderation. Birds and other animals — including grasshoppers, which are cannibalistic — feed off of the insects. But when the population mushrooms out of control, it can have consequences. Because grasshoppers are so large, and travel in big groups, Bundy said, they can actually become road hazards.

And, “they eat everything,” Bundy said.

One of Bundy’s research foci is the integrated pest management of insects affecting crops in New Mexico. IPM uses a variety of methods — including some pesticide use — to control pests, but without relying too heavily on any one approach. The approach aims to avoid pesticide resistance, which can develop in populations and make chemical pest treatments less effective.

Bundy said that there are some physical approaches that could be taken this season, including adding fences, vacuuming insects and making rangelands less attractive to the insects. But he continued, that the season is almost over and the infestation should let up for a while.

“They won’t be around forever,” Bundy said.

Several ranchers hope APHIS and BLM will be able to tackle future problems with grasshoppers.

“Hopefully we can have minds come together and find a solution … that everyone can benefit from,” Hutchison said.