Two models of the potato leafhopper were created to help manage this serious pest of alfalfa. One emphasized the population dynamics over the whole season and the effects of injury on alfalfa yield. The other emphasized leafhopper dynamics over a single alfalfa-growth period and validation of the results. Because the first model was linked to a model of alfalfa, systems analysis permitted the identification of economic thresholds. Both modeling approaches indicate that systems analysis should be a valuable tool for alfalfa pest management in the future.