White grubs that attack turfgrass lawns are the immature larval stage of several kinds of beetles. Japanese beetle grubs are about an inch long, curl into a "C" shape when exposed, and have a yellow-brown head, white body and black or gray posterior. June beetle grubs are also about an inch long, are white with brown heads and usually curl into a C. Masked chafer grubs are white when they hatch but turn gray with a brown head after feeding. Green June beetle grubs are larger (about two inches), are rarely curled, and are more tan in color than white.

Most grubs hatch in the soil from eggs in mid summer and feed on the roots of grasses through fall. In winter the grubs move further underground and return to near the surface in spring where they mature into adults.

Grubs have a general pattern of behavior that is destructive to lawns and turfgrass. Japanese beetle, masked chafer, and June beetle grubs all feed on the roots of the grass, destroying the anchor for the turf above. When grubs invade in sufficient numbers the grass in the affected areas can be peeled back like a carpet. Green June beetle grubs feed on decaying organic material, not turfgrass roots; however they do tunnel extensively through the grass root system which causes damage.

There are natural predators of these destructive pests - birds, especially starlings, will flock to areas where the grubs are close to the surface. Animals such as skunks and moles also feed on the grubs but inflict their own damage to the lawn. A bacterial disease called milky spore disease is sometimes effective for killing the grubs over time but will not prevent beetles from entering from other areas. Probably the most successful strategy to eliminate the grubs is to combine controls for adult beetles (see Japanese beetles, below) and to apply an insecticide designed to penetrate the soil and kill the grubs before they can damage the lawn.