A new pest of midwestern soybean has invaded eastern and central Iowa. Initial identifications and reports from neighboring states suggested that this insect was the cotton aphid (also known as the melon aphid) but it has now been positively identified as the soybean aphid, Aphis glycines. This aphid is native to southeastern and eastern Asia and may have been in the United States during the past couple of years. It was first detected in Wisconsin this summer and has now been confirmed in Minnesota, Illinois, Michigan, and Ohio.