Sod webworms are one of the most common and damaging lawn insects in this country. They are buff-white moths, about 3/4-inch long, that fly zigzag patterns just above the grass at dusk, laying eggs. Gray, tan, or green larvae up to one inch long feed on shoots and crowns of blue-bent and zoysia grasses and fescues, causing irregular, close-clipped brown patches. There may be as many as three generations a season: May, July, and September. Discourage webworms with soapy water. If that doesn't work, mow, then water well, a day before treating the lawn with Bacillus thuringiensis, bendiocarb, chlorpyrifos, diazinon, or ethoprop. Spray dry grass late in the day. Don't mow or water the lawn for 48 hours.
