Researchers at the University of Wisconsin were the first to notice the pests. The agronomists there were surprised to find large numbers of aphids feeding on soybean leaves and stems in their research plots earlier this summer. Aphids are traditionally not considered to be pests of soybean production in the United States. They also alerted researchers in other Midwestern States of what they had seen and asked if any other states had been noticing similar problems. As the infestation continued and began to increase in areas of Wisconsin, the researchers sent samples to experts at the Illinois Natural History Survey and to the USDA, who on August 15 identified the pest as Soybean Aphids.
Soybean aphids are a significant pest of soybean production in the plants native home in Asia.
The problem was first found in Michigan in a field located near Hartford MI on August 7, 2000. Closer inspection revealed tremendous amounts of aphids feeding upon the upper stems just below the uppermost leaves on the most severely affected plants. Areas in the field that were still green also had aphids feeding on the plants but seemed to have less aphids feeding on the stems and more aphids feeding on the underside of the leaves. I removed a couple of plants from the field, covered them with plastic, and brought them to the field day. Dr. Chris DiFonzo, MSU Field Crops Entomologist, took the samples back to the lab where they were later confirmed to be the same species that had been seen in Wisconsin .