Soybean aphid, Aphis glycines Matsumura, a native of eastern Asia, was first discovered in North America in July 2000 in Wisconsin and subsequently in a total of 10 North Central U.S. states by September 2000. Currently, soybean aphid has spread to 20 U.S. states and three Canadian provinces, putting >60 million acres of soybean at risk to crop injury caused by this exotic insect. The life history of this species has been studied by a number of entomologists and crop protection specialists, and here we provide a summary of the observations made by ourselves and our colleagues. The soybean aphid has been observed at all stages of a heterecious holocyclic life cycle and seems to be adapting to a large geographic area of the North Central United States. Soybean aphid uses native and exotic primary hosts found in North America, specifically Rhamnus cathartica L. and Rhamnus alnifolia L’Hér. The aphid’s principal secondary host is soybean, Glycine max (L.) Merr., but there seems to be a lengthy gap in early spring between the production of alatae on buckthorn (Rhamnus spp.) and the occurrence of soybean. In the fall when soybean is senescing, a biological bottleneck is created as the aphid must develop sexual morphs on soybean that emigrate back to the primary host to complete the sexual phase of its life cycle. During the summer, A. glycines is prone to develop winged morphs during any generation on soybean, which puts much of the soybean crop at risk of invasion by this exotic species, even if the insect does not overwinter locally. The integrated pest management challenges presented by the aphid require a deeper understanding of its biology as it adapts to North America.