The soybean aphid (Aphis glycine) is a newly introduced pest in Midwest soybean.  Native to Asia, these aphids were common in southern Wisconsin during the 2000 growing season.  Plants heavily infested with aphids were stunted, had distorted or cupped leaves, were covered with honeydew and black mold, and sprinkled with white skins shed from growing aphids.  During mid-season, fields with an estimated 500-1000 aphids per plant were not uncommon.

The illustrations below show plants that sustained high aphid numbers, but had only slight symptoms of injury:

Soybean infested with soybean aphid Click here for original image (205 kb)

Soybean with aphid skins Click here for original image (206 kb)

Below are two images of ants tending soybean aphids.

Ants with soybean aphidsClick here for original image (47 kb)

More ants with sobyean aphidsClick here for original image (223 kb)