Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), continues to be an economically important insect pest of soybean in the northcentral region of the United States since its first report in 2000. Control has traditionally relied on foliar applications of pyrethroid and organophosphate insecticides; however, recent confirmed failures of pyrethroids in the region have prompted immediate management concerns. Insecticidal modes of action are limited, and there is a need for assessing residual efficacy of exisiting and new insecticides for soybean aphid. We developed a field-based protocol to evaluate the residual efficacy of treated foliage, and tested our method with two insecticides. Our residual testing protocol can be utilized for residual efficacy evaluations of other pests and in other systems.