Warm weather spur grasshoppers to hatch; aerial pesticide spraying begins in Wyoming

Grasshopper spraying begins as pest species hatch

CHEYENNE, Wyo. — Grasshoppers capable of stripping rangeland bare of grass are starting to hatch in parts of Wyoming, prompting the start of aerial pesticide spraying to mitigate an outbreak, pest control officials said Tuesday.

County weed and pest districts have already begun or plan to start aerial insecticide spraying this week in Johnson, Goshen, Campbell, Crook and Converse counties, said Slade Franklin, weed and pest coordinator for the Wyoming Department of Agriculture.

The Bureau of Land Management said Tuesday that it has begun treating federal lands in Niobrara, Weston, Crook and Johnson counties.

Landowners and government officials spent months preparing for a possible grasshopper outbreak after autumn surveys indicated that parts of Wyoming could face infestations this summer. The grasshoppers are voracious grass eaters and can devastate ranch- and farmland during an infestation.

The weather heating up Wyoming in recent days is spurring the grasshopper eggs to hatch. Cool temperatures and moisture this spring may have delayed, but not stifled, the onset of the outbreak, officials said.

“Unless we have a really big change in the weather, I think (the grasshoppers) are pretty safe right now,” said Scott Schell, assistant extension entomologist at the University of Wyoming.

Schell said he visited Niobrara County on Friday where there were more than 50 pest grasshoppers per square yard. Rod Litzel, coordinator of the Johnson County Weed and Pest District, said he’s seen similar counts in his county.

Grasshoppers are considered economically damaging when they reach a concentration of 14 per square yard, at which point they can cause about 30 percent forage loss over a season, Schell said.

Litzel said landowner reports of grasshopper outbreaks started picking up in the past two days. The Johnson County district began its $2 million grasshopper spraying program last week, and Litzel said the district should be able to complete spraying next week, depending on conditions.

Schell said it’s crucial to treat grasshoppers early in their life cycle. The standard insecticide, Dimilin 2L, is a growth regulator that kills grasshoppers that consume the insecticide in the nymphal stage before they become adults.

The chemical is administered by crop dusters that spray alternating swaths of land.

Schell said early preparation by weed and pest districts should help protect forage for livestock and wildlife, which otherwise could suffer despite good grass growth.

“If you did nothing about them, in six weeks they would be adults and be flying around, and you would have a greater appreciation of the damage they would cause,” he said. “By acting preemptively, they’re going to prevent that.”