Adult females are responsible for most injury to soybeans. Spider mites have piercing-sucking mouth parts and feed by sucking sap from the plant. Mite injury somewhat resembles herbicide injury or some foliar diseases. Typical damage symptoms are small yellow speckles on the leaves. As injury becomes more severe, the leaves become yellow and develop brown lesions, and the plants die.
Rain is the surest way to stop the spread of mite damage.
The potato leafhopper is a pest primarily of alfalfa in Pennsylvania, but can occasionally infest soybeans. The insect migrates into the state around mid-May and begins feeding on plants in the legume and rose family. When infestation levels are high in alfalfa, leafhoppers may move into soybeans. Also, if a soybean field is next to a recently cut alfalfa field, leafhoppers may move to the soybeans and cause injury. If plants are small, economic damage is possible.