Populations of the Twospotted spider mite, Tetranychus urticae Koch, increase during periods of hot, dry weather. Representative grain yield reduction potential in soybean (40-60%), field corn (23%) and silage corn (17%) are significant (Klubertanz, 1994; Bynum, pers. comm.).
Spider mites damage plants by piercing cells and sucking sap. Mites often go undetected until damage is severe because of their tiny size and because spider mite feeding and drought stress symptoms are similar. It is important to be aware of twospotted spider mite potential under these conditions, recognize plant damage symptoms, and be able to identify live mite colonies in the field.