by Rick Mooney
Editor, eHay Weekly

Hay growers and livestock producers in Western and Plains states are bracing for a potentially severe grasshopper outbreak this summer.

“In some states, we may see the highest populations of grasshoppers that we’ve seen in many years,” says Charles Brown, national grasshopper suppression program manager at USDA’s Animal and Plant Health Inspection Service (APHIS).

Based on fall 2009 APHIS surveys of adult grasshopper populations in the 17-state region covered by the APHIS program, Brown pegs Wyoming, Montana, North Dakota, South Dakota and Nebraska as states most likely to see severe outbreaks during the upcoming growing season. Utah, Idaho and Nevada could also see significant infestations.

According to APHIS’ 2010 Rangeland Grasshopper Hazard Map, nearly 48 million acres region-wide could see populations of 15 or more grasshoppers per square yard.

Spring weather will play a key role in determining just how severe outbreaks are, says Brown. “Warm temperatures, with little rainfall, are favorable for the hatching and development of grasshoppers. On the other hand, cool and wet conditions could limit grasshopper populations.”

USDA is currently exploring funding options for cost-sharing control efforts on federal, state and privately owned rangelands. “We’ll do our part to cooperate to the extent that budgets allow,” he says.

Some individual states are also taking steps to prepare for severe grasshopper outbreaks. Wyoming has announced a $2.7 million plan to help local pest districts and state agencies pay for spraying programs this summer. Last year, according to surveys, populations exceeding 15 grasshoppers per square yard were found on nearly 2.9 million acres in the state.

The southwestern, south-central and west-central regions of North Dakota could be hot spots for grasshopper outbreaks in 2010, says North Dakota State University Extension entomologist Janet Knodel. Producers will want to begin scouting their rangelands in early June following the hatch.

As a guideline, she says, treatment measures generally are economically warranted when nymph populations reach 30-45/square yard or adult numbers reach 8-15/square yard. “It’s best to get on top of the situation when the grasshoppers are emerging. Young grasshoppers are easier to kill.”

Knodel adds that several pesticides are labeled for controlling grasshoppers in hayfields and pastures in North Dakota, including Sevin, Dimilin 2L, Malathion 57EC and Mustang Max EC. “Some of these products require waiting one day after treating before you cut hay or allow livestock to feed,” she says. “So you’ll want to be sure to read labels carefully.”

Check out an APHIS fact sheet on grasshoppers and Mormon crickets