These beetles are about one inch long and reddish brown. True white grub adults feed at night on the leaves of oak, crabapple, ash, and other trees. Carbaryl, sold as Sevin, is effective against these adults. Larval treatment on turf is should take place in late summer. Honeylocust plant bug numbers appear to be light in most areas of central Illinois.
Numbers are also low at The Morton Arboretum.
However, a landscaper in Rockford reports large numbers. Ash plant bug numbers are high enough to cause obvious stippling damage throughout the state. These numbers are usually not large enough to warrant treatment. This borer is particularly destructive to young maples and aging rose-family trees. On young maples it bores spirally up the trunk, starting near ground level, and feeds in the cambium just under the bark.