If you cut it at ground level, you may have to cut three or four times before it dies. Irregular patches of slow-growing, yellowing grass and turf that is loose because its roots have been eaten. Cut a foot-square piece of sod five inches deep and turn it over. If you see 10 or more grubs, take action. Attract birds, which are the natural enemies of beetles, with berry bushes, trees, and feeders.
Plant wildflowers to lure parasitic insects, also enemies of beetles.
Apply milky spore disease, a biological control for grubs. Use predatory nematodes to control grubs. Nematodes attack while swimming, so pour them on damaged areas with a watering can. Don't use beetle traps, which can attract more than they kill. Damaged areas are small yellow or brown circles.