Thursday, July 08, 2021

Grasshoppers Cover the West

The extreme and prolonged drought affecting the western United States has generated another plague Pharaoh would be familiar with: grasshoppers. The dry conditions are favorable to large hatches of grasshopper eggs, normally kept in check by natural forces. Eastern Oregon has been particularly hard hit by the winged insects; thirteen western states report crop and range damage from grasshoppers. Their prolific appetite for grass make them a formidable pestilence, costing thousands of dollars to control. One eastern Oregon rancher estimated a $50,000 loss in range land forage. A sixth generation rancher near the California border told an interviewer, “The damage that they do when they come into crops is just absolutely horrific.” [photo credit: AP]

Broadcasting insecticides in problematic. Untargeted chemicals kill other often beneficial insects as well as contaminate wildlife and soils. Dimlin, the most specific insecticide is effective only against young grassphopers and between molts when adults shed their exoskeletons to grow. If the window is missed, farmers must wait until next year. In Oregon grasshoppers are hatching early and maturing sooner due to climate change making suppresion more challenging. This year's suppression campaign is recogned to be the largest in 35 years. Left to their own fate, grasshopper bursts die off after predators and pathogens catch up to the population growth. Grasshopper popularity as prey makes them key to ecological equilibrium most of the time, until population density turns them into pests.