The soybean aphid, Aphis glycines, was first found in Wisconsin (and North America) by UW soybean researchers in July 2000. Following that initial discovery, outbreaks of the aphid were reported in soybean fields throughout southern Wisconsin. The impact of aphid feeding was devastating to soybean yields in the most heavily infested fields, with aphids literally covering the plants. In an experiment on the UW Arlington Agricultural Research Station, we were able to measure about a 6 to 8 bushel yield loss as a result of a moderate soybean aphid infestation. In addition to this direct feeding injury, the soybean aphid is known to transmit viruses that are pathogenic to soybean plants.