Both the adults and the immature feed on plant juices from the underside of leaves. Their feeding causes yellowing, curling and bronzing of the leaves. A close examination will show fine webbing on the lower surfaces of the foliage. Mites are often found in soybeans about the time corn is silking. They usually move in from fence and hedge rows, especially in periods of drought as the weeds dry down.
Mites also move into soybean fields as grain and other crops mature.
There are many generations per year. Four or more mites per leaf or one severely damaged leaf per plant prior to pod-fill causes concern, as crop yields are affected. If mites have exceeded the damage threshold, apply an insecticide. If the infestation is caught early enough, it is necessary only to treat hot spots on the edges of the field where the mites are moving in from their overwintering sites. This will help to prevent the spread of mites to other parts of the field and may reduce the need for further treatment.