Insecticide could reduce grasshoppers for next year |

Insecticide could reduce grasshoppers for next year

For the past two years, landowners have not only been battling drought and fires, but dealing with grasshopper infestations across the west. What can farmers and ranchers expect late summer 2022? Unfortunately, the winter wasn’t cold or wet enough to kill the destructive insects.

South Dakota State University Entomology Field Specialist Patrick Wagner said grasshoppers are as abundant as last year and could be a little worse in some areas.

“We had a late freeze and mild winter in South Dakota, which means the grasshoppers had plenty of time to lay eggs last fall and many of those survived. Areas near water sources seem to be the hot spots, such as the counties along the Missouri River,” Wagner said. “For now, people can spray insect growth regulators (IGRs) if the grasshoppers reach threshold levels. IGRs are a good option as long as they’re still in the nymphal stages.”

Landowners will be seeing more adults as August and September arrive, so Wagner said treatments will need to transition to a broad-spectrum insecticide that is labeled for grasshoppers.

“I haven’t heard any reports of grasshoppers moving into crops yet, but that could change if drought conditions worsen,” Wagner said.

University of Wyoming Extension Entomology Specialist Scott Schell said he believes Wyoming has fewer areas with grasshopper problems this year. However, there are always hot spots of various species to be found.

“I drove through a swarm of clear-winged grasshoppers flying across Highway 487 south of Casper last week,” said Schell. “I looked at a crested wheatgrass pasture just mowed by bigheaded grasshoppers located just across the state border in South Dakota east of Newcastle, Wyoming on Tuesday, and also recently saw a photo of lots of grasshoppers on the road near Scobey, Montana.”

Schell explained that if grasshoppers haven’t hatched, cold and wet spring weather has little impact on their survival and may actually benefit them in that they need some soil moisture for hatching and will at least have some green grass to eat to get started. Last year the severe drought in some areas with grasshoppers may have reduced grasshopper egg production and viability due to less green food than optimal for them.

“If people sprayed their infestations last year and got good control of grasshoppers before they put eggs in the ground and didn’t get reinvaded subsequently, they should not have had re-infestation this year. That is one of the reasons we emphasize treating grasshoppers before they are sexually mature,” Schell said.

Ranchers who sprayed for the destructive insects last year have had some relief. Nancy Ereaux who ranches in Malta Montana, said they, along with two other neighboring ranches, sprayed 12,000 acres last year on June 23 using Dimlin, with under the assistance and direction of the Animal and Plants Inspection Service (APHIS).

“This year, we have some, but not even close to the number we had last year,” Ereaux said.

Gary Heibertshausen, a sheep rancher from Alzada, said they are fairly grasshopper-free this year since they sprayed last year.

“I believe spraying really helped greatly reduce the numbers,” Heibertshausen said. “ We just bought some small square bales from a neighbor who didn’t spray and that hay is full of them.”

Shay Richter, an agronomist for Wilbur Ellis as well as a small grains farmer, said the grasshopper populations this year depends on location, noting that they’ve been abundant around Big Sand, Montana and towards Hingham.

“There has been some damage to barley⁠. You really need to watch what you’re spraying to make sure you have the correct preharvest interval on a chemical. A lot are 21 days. Some of the pulse crops are getting dinged up and grasshoppers are starting to munch on the pods across the High Line and Golden Triangle area,” Richter said.

Since grasshoppers keep shedding their skins, the smaller they are when you spray, the more economical—about $1 an acre—it will be. Spray early in the morning before there are other insects moving around.

Richter said that crops are running at about half of what they normally have at this time across the Golden Triangle, “so it’s not a complete disaster. However, a lot of areas around Carter and Chester got hit by hail, so trying to control grasshoppers on top of remains critical to save what vegetation remains.

He added that not only do grasshoppers damage a crop yield, but a farmer can get docked at the elevator if there is too much foreign material in with your crops.

“That’s just another reason to spray early, then hope for a cold winter,” Richter said. “I’ve heard that grasshoppers come in three-year intervals, and this is our third year, so hopefully this is our last year for a while.”

Landowners dealing with grasshoppers can contact their local extension service, local agribusiness services and APHIS to discuss options for spraying and other methods of grasshopper control.

Concerned landowners can find their State Plant Health Director here ( (

Start a dialogue, stay on topic and be civil.
If you don't follow the rules, your comment may be deleted.

User Legend: iconModerator iconTrusted User


Loading comments...