Which insects present the biggest risk to soybean production?
Most insect pests of soybeans in Illinois are only of occasional importance. That is–economic injury doesn’t occur very often in most fields. This situation can change rapidly in drought years. In 1988, a severe drought throughout much of the Corn Belt led to an outbreak of twospotted spider mites. Insecticide use on Illinois soybeans went from about 2 percent of the acres sprayed to over 50 percent. In non-drought years, the primary insects of concerns are the defoliators. This group of defoliators includes bean leaf beetles, green cloverworms, grasshoppers, Japanese beetles, and woollybear caterpillars. Generally, treatments are not recommended unless defoliation levels reach 30% before bloom and 20% between bloom and pod fill. In general, most growers overestimate the level of defoliation. Other insects like stink bugs have piercing-sucking mouthparts and cause injury to developing beans within pods. Bean leaf beetles and grasshoppers also can cause yield losses due to their feedin
