The Pacific Northwest is facing what could possibly be the most devastating grasshopper infestation in the past 30 years, though it may not be as large as initially projected, according to WSU scientists and other researchers.

The United States Department of Agriculture keeps track of the number of grasshoppers that infest the state of Washington on a yearly basis, said Richard Zack, Washington State U. associate professor of entomology.

“Those numbers have been going up each year from 67,000 infested acres in 2006 to just over 451,000 infested acres in 2009,” he said.

With the dramatic increase in grasshopper populations in the past few years and the relatively mild winter that Washington experienced this past year, researchers are predicting that the upcoming year could be even more devastating than last year.

Some of the most at-risk areas in Washington are the desert regions near Othello, Yakima and the Tri-Cities. While Pullman faces some risk of infestation, it is not predicted to be as high as these areas.

“The grasshoppers develop on open rangeland and then move into farmland once the open range starts to dry out,” Zack said. “Grasshoppers will move into those farmlands and will feed on the crops. If the numbers of grasshoppers are large, they can eat a lot of the vegetation and cause significant damage.” One thing that Zack thinks can help contain the infestation is the unseasonably wet and cold spring that the state is experiencing, which could possibly help control the grasshopper population this season.

“This cool and wet spring may serve to lessen grasshopper numbers,” Zack said. “As they are now hatching from eggs that have overwintered in the soil, the wet and cool spring may lead to death among many of the young grasshoppers.” The term overwintered means that the eggs have spent the winter season developing in the soil.

Despite predictions that grasshoppers could emerge in record numbers this year, Zack says the Northwest is currently at the climax of grasshopper population and expects their numbers to begin to fall over the next couple of years.