Annual white grubs, Cyclocephala spp., complete their life cycle in one year. Adults are tan, about 5/8 inch long, and have a dark, mask-like marking over the eyes. Adults are normally present from late June through July. They are highly attracted to lights, and are frequently observed around windows or porch lights. Adult masked chafers do not injure turf or other vegetation.
Masked chafer beetles deposit eggs in the top 2 inches of soil, often in small clusters. Small grubs hatch during late July and early August and immediately begin feeding on grass roots. Most damage occurs in late summer and early fall after the grubs have reached the second and third larval stages. With the onset of cold weather, grubs move deeper in the soil to overwinter. As soil temperatures warm in the spring, they return to the root zone, feed for a brief period, pupate, and emerge as adults to begin a new cycle. Spring feeding is not as destructive to turf as late summer and fall feeding. Consequently, spring treatments are rarely required.