They overwinter in litter and trash around fields. In early spring, beetles are active on weeds and then move to corn seedlings during May through June. Infestations are more severe when a cold spring follows a mild winter. Adult beetles leave numerous, small, circular feeding holes and bleached out spots or stripes on the corn leaves. Such direct feeding is insignificant unless large numbers of beetles attack slow-growing corn, especially during a cold spring.
Infestations are generally uniform throughout the state.
In untreated plots, up to 90 percent of the ears can be expected to show feeding signs. Eggs are laid on the leaves when the plants are small. Injury to the foliage occurs before tasseling. The corn leaves are ragged when they grow out, but this damage usually does not seriously affect the crop. The new generation of moths lays eggs on fresh corn silk as it appears.