The larvae of several kinds of beetles, white grubs are one of the most common lawn pests. They're thick, whitish, C-shaped worms that grow from 3/4- to 1-l/2 inches long and eat grass roots underground. If your lawn is infected, the turf will feel spongy and pull up easily. Dead brown patches develop. The worst damage occurs in April and May, although you also may see some damage in September and October. Small animals tear up the sod to feed on the grubs. To solve the problem, water the area well, using a wetting agent if the soil doesn't absorb quickly. Then apply diazinon or isofenphos as directed, watering thoroughly immediately afterward. Don't allow runoff. Treat the grubs of Japanese beetle with milky spore disease.
