The adults of the annual white grub are tan, 1/2 inch long beetles that emerge from the pupae in June. The larvae are white with a brown head. When found feeding on roots in the soil, they have a characteristic "C" shaped body.
In the summer, adult beetles are drawn to well-watered lawns for egg laying. The adults are nocturnal and do not feed. Larvae hatch and feed on turfgrass roots, with damage usually appearing in mid August and possibly continuing through the fall. Larvae overwinter in the soil and resume some feeding the following spring until they pupate in late spring/early summer.
Annual White Grub is the most serious turfgrass pest in Illinois. Grubs feed on turfgrass roots, that will damage and can kill the grass. Grub damage appears as brown areas and when enough feeding damage has occurred, lawns may be rolled up like carpeting. Moles, skunks, and birds often dig for the larvae and also damage the lawn.
Grub damage can vary from year to year. During dry summers, grubs may be more concentrated in well-watered lawns. During wet summers, grub damage may not appear at all. It is important to check for the presence of grubs before deciding if treatment is warranted.
Non-chemical: During a dry summer, allowing the lawn to go dormant may help reduce egg-laying activity.
Chemical: Controls should be directed at young and newly hatched grubs. Contact your county Extension office for current pesticide controls.