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 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.