Usually the upper portions of plants are damaged first because the beetles like warmth and sunshine. Aesthetic quality of the plant is reduced, and it is subject to more stress as a result of the beetle feeding. Don't confuse Japanese beetle with Asian longhorned beetle that has appeared in the Chicago area. The Japanese beetle has been in Illinois for some time and is gradually spreading west. Also look for white tufts of hair on the back end of the body.
Japanese beetles are very active during the day and tend to appear in large groups on plants.
Once they first appear, adult beetles are usually out for about 6 weeks, which means most should be gone by mid-August. After mating, beetles lay their eggs in the soil. Eggs hatch into grubs, which may feed on various plant or turfgrass roots. Thus it is possible for lawns to be damaged later this summer by the grubs. Japanese beetles overwinter as grubs in the soil, and emerge as adults again next June to start the cycle over again.