UW Extension Entomologist Says Warmer Climate Could Boost Grasshopper Numbers

University of Wyoming Extension Entomologist Alex Latchininsky says a wetter, warmer climate may contribute to future locust outbreaks like that harassing Argentinians, and also could boost future grasshopper infestations in Wyoming and the West.

Officials say Argentina faces its worst plague in more than half a century, with the New York Times last month reporting farmers in 2015 sighted locust clouds more than 4 miles long and nearly 2 miles high.

The locust species causing havoc in Argentina is the South American locust, Schistocerca cancellata, Latchininsky says. Because of the crops it feeds upon, economic importance is high.

Latchininsky, a professor in the Department of Ecosystem Science and Management, was asked by The Weather Channel how climate change may affect future locust outbreaks and how insufficient control efforts may contribute. Latchininsky, in the College of Agriculture and Natural Resources, is an international consultant for the United Nations Food and Agriculture Organization, and advises agencies in the United States on grasshopper control and monitoring.

Climate change may influence the South American locust in two ways, he says.

The Moroccan locust expanded its ranges northward. (Alex Latchininsky Photo)

More abundant rains in its breeding areas could trigger an outbreak due to likely producing three generations instead of one, and higher temperatures may allow the locust to expand its range to the south, Latchininsky says. 

Some locust species (for example, the Moroccan locust Dociostaurus maroccanus) in Central Asia expanded its distribution ranges to the north because of warmer temperatures.

Grasshoppers in Wyoming also could get a climate-change boost by developing faster and producing more offspring, he adds.

Some Western Hemisphere subtropical grasshoppers, like the Moroccan locust, have expanded their ranges northward. The gray bird grasshopper, Schistocerca nitens, whose northern-most boundary has been south Texas, was spotted several times in Wyoming near Cheyenne and Lusk.

“This shows the great migratory potential of these grasshoppers,” Latchininsky says. “Like locusts in the Old World, they can expand their ranges to the north when temperature rises.”

Locust swarms from South or Central America invading Wyoming is unlikely, he says, but last year showed an upsurge of the native grasshopper numbers in the state.

In a couple of years, that may lead to a widespread grasshopper outbreak similar to that in 2010 when more than 6 million acres of rangelands were protected from these pests, Latchininsky says.

As for South America, efficient monitoring systems should be established in the South American locust’s traditional breeding areas in the north of Argentina for control, Latchininsky says. Some of those areas are hard to access and are insufficiently monitored. He advised breeding areas should have anti-locust treatments, against early-instar hoppers.