Young grasshoppers have begun chewing up bean rows on the edges of fields in northeast North Dakota.
“They’re coming out of the ditch. They’re taking the outside soybean rows,” said Brad Brummond, Walsh County Agricultural Extension agent. “At least one field I saw, they’re 20 feet into the field.”
The grasshoppers are in the nymph stage, but there are a lot of them, Brummond said. When grasshoppers hatch from the egg, the nymph is about the size of a wheat kernel, according to a North Dakota State University Extension Service website about grasshoppers. Nymphs, which don’t have wings, pass through five to six growth stages.
Grasshoppers typically feed on grass, weeds and agricultural crops. They flourish in hot, dry weather. On the flip side, wet weather increases diseases and delays grasshopper development.
Crop production experts suggest scouting regularly for grasshoppers because the insect’s population varies from year to year.
“My concern is that small grasshoppers become big grasshoppers," Brumond said.
“I have one field, there were five acres gone,” he said. “When I don’t have any plants, that’s an economic threshold.”
The economic threshold that warrants spraying to control grasshoppers is 50 to 75 grasshoppers per square yard if the insects are in the field margin and 30 to 45 square feet, according to the NDSU Extension Service website.
There are a variety of insecticides approved for control of the nymphs, according to Brummond, who also is advising Walsh County growers to monitor alfalfa fields for blister beetles before they cut it for hay.
Blister beetles, which are black, gray or fluorescent, contain a poison on their shells that blisters skin. The beetles, which are toxic to horses, were found in a Pembina County garden.
“They’re very toxic to horses. They’ll kill horses, if you get enough of them,” Brummond said, noting that, when alfalfa hay is crimped, it crushes the beetles so they release the toxin.
Alfalfa fields infested with blister beetles can be sprayed with an approved insecticide or producers can wait to cut until the beetles leave.
“Just because they’re here today, doesn’t mean they’re here tomorrow,” he said.