There have been a few incidents of chafer damage on turf grass in Colorado. The larvae are routinely found in compost piles. Chafers and May or June beetles are distributed throughout Colorado, but are found in greater numbers in grassland areas.
Chafer beetles are in the scarab family of insects which include May or June beetles. Adults are heavy-bodied insects with spiny legs. The front pair of legs are sometimes thicker for digging. This family has unusual antennae that have elongated club-like knobs at the terminal end. Scarab larvae are c-shaped, white or light colored with a distinct dark head and dark legs. Larvae of most scarab species are scavengers but chafer beetle larvae feed on plant roots and can be pests in turf grass.
Hand picking is the best way to eliminate larvae or adults from compost piles. Do not spray an insecticide on a compost pile. If you find dead spots in turf grass, dig and look for white c-shaped grubs.
Insecticide treatments include carbaryl, imidicloprid and halofenozide.