Be sure to note any precautions and restrictions, and always read and follow the pesticide label. In areas where soil insects or billbugs are prevalent, apply one of the recommended granular systemic insecticides at planting. These protect young plants for several weeks and help get the corn off to a good start Determining whether or not to apply a foliar insecticide for pests such as corn earworms, armyworms, or European corn borers is often difficult. Many times you may have an insect in every whorl without sustaining much loss in yield. If you decide to apply a foliar spray, use ground equipment and lots of water.
Aerial sprays are usually effective only if the larvae are exposed, feeding on the leaf surface.
It is difficult to control insects that are feeding deep in the whorl. Borers such as the European corn borer can be controlled only before they enter the stalk or ear. Once inside the plant, they cannot be controlled.