Adult May beetles are active and quite numerous in central Illinois. These insects feed at night on tree foliage, particularly ash, crabapple, and oak. Feeding damage on the edges of leaves that isn’t associated with insects may be the result of these insects feeding at night. If practical, check some of these locations after dark. You are likely to see 1-inch-long, reddish brown to dark brown, stocky beetles feeding on the leaves. Carbaryl (Sevin) and other labeled insecticides should provide effective control.