Grubs are the most serious and destructive lawn insect pest in Illinois. While not all lawns will get grubs and the extent of grub damage varies from year to year, there are some important points to consider concerning managing grubs in lawns.
Grubs are typically white, with a characteristic "C" shape body when found in the soil feeding on lawn roots. Grubs are the larval stage of beetles.
A common grub species in our soil is the larval stage of the Japanese Beetle. Eggs are laid in the soil in mid-summer, primarily on low-cut, well-watered lawns in full sun, often near pavement. Damage from grubs typically starts in mid-August and may continue until early October. Other species may damage lawns but are becoming less common than the Japanese Beetle. Monitoring and control of these species is the same. The true white grub (May or June beetle), for example, typically has a 3-year life cycle, meaning it could potentially damage lawns throughout multiple seasons. Adult Japanese beetles can be a serious problem on many crops and ornamental plants. Additional information on adult Japanese beetle.