Widespread infestation of soybeans with soybean aphid across much of Wisconsin during the 2000 growing season prompted us to examine the economic impact this insect poses to the soybean crop in terms of direct yield losses (the potential yield losses due to virus transmission by the aphid are not addressed here).

The goal of this study is to examine the yield loss relationship of the soybean aphid to soybeans and attempt to quantify the damage caused by this insect. Furthermore, we would like to develop an economic threshold that will allow soybean producers to make intelligent decisions regarding aphid damage and control methods.