The overwintering ability of the soybean aphid (Matsumura) was studied in the Red River Valley of Minnesota and North Dakota from October 2004 to June 2005, and the survivability of eggs was described. Eggs were deposited upon buckthorn (Rhamnus cathardica) in October, and tested under simulated snow-covered conditions, and in exposed non-covered conditions. Eclosion began in April and was completed in 2 weeks. No difference between covered and uncovered conditions were recognized. Overwintering survival was virtually 100% in both treatments. Alate dispersal began in May and continued into June. The results of this experiment validate that not only is soybean aphid able to successfully overwinter in this region, but is able to colonize soybean production fields emerging in May.