Since its discovery in the United States in the upper Midwest in 2000, the soybean aphid (Aphis glycines Matsumara) has spread to over 20 states. The soybean aphid overwinters on buckthorn and after spring movement to its primary host, soybean, it reproduces rapidly and reaches peak populations in late July. At this time direct feeding damage to soybean is widespread with early senescence and reduced pod set, seed quality and yield reported throughout the Midwest. As populations peak in soybean, winged forms are produced in huge numbers which migrate to new crops seeking new host plants and/or overwintering sites. This mass migration of winged aphids from over 20 million acres of infested soybean in the Midwest – Voegtlin and Onstad (2003) estimated that over 400 million soybean aphids emigrated from a single 80 acre field in a single day – represent a significant threat to other crops grown in the region.