Alfalfa is host to an abundance of insect pests that vary in seriousness. One of these, the potato leafhopper, is considered the primary insect pest of alfalfa in Iowa (Figure 1 ). This insect feeds by sucking plant fluids through its straw-like mouthparts. Feeding can cause serious injury to alfalfa if pest numbers are high, and it is usually too late to treat by the time symptoms become visible. Leafhopper feeding deprives the plant of nutrients and creates wounds where disease can enter. However, the most important effect results from a small amount of saliva that is left in the plant wound. Leafhopper saliva causes plant cells to harden, which restricts the flow of nutrients throughout the plant and causes yield loss.