If you see large dead patches of lawn in your yard throughout the late summer or early fall, you may have a white grub problem. White grubs feed on the roots of your grass. Without roots, your grass quickly dies. One sign of a grub problem is if you can lift the dead patches of grass off your lawn easily like a carpet. Insecticides, when applied at the correct time, will get rid of the grubs in your lawn. These are best applied in the late summer when grubs are most active.
Examine your lawn to ensure you have a white grub problem and not some other lawn disease. Use a flat spade and cut out a six-inch by six-inch square of lawn. Lift it up, and examine the soil around the grass roots. If you see more than two or three grubs in that square, you have a white grub problem. White grubs are cream-colored larvae that have three distinct pairs of legs. They have an amber-colored head and are fairly large. Examine multiple areas of the lawn to see which areas need treatment.
Cut back on irrigation. Water your lawn deeply, but infrequently. Once a week is sufficient for most lawns. Grubs need moist soil to hatch and survive. If your soil dries out between waterings, your grub problem should be reduced.
Apply an insecticide that is geared toward white grubs in late July or early August. Apply as directed in the areas that need to be treated.
Apply a preventative insecticide the following year. Products containing imidacloprid, thiamethoxam, halofenozide, clothianidin or chlorantraniliprole target newly hatched grubs. Apply as directed about a month before grubs hatch (early July in most locations).