
Problem: Webworms

Problem Info
From mid-May to October the grass turns brown in patches the size of a saucer in the hottest and driest areas of the lawn. These areas may expand to form large irregular patches. Grass blades are chewed off at the soil level. Silky white tubes are found nestled in the root area. Inside are light-brown or gray worms with black spots, from 1/4 to 3/4 inch long. Called sod webworms, these are the larvae of lawn moths. They can kill an entire lawn in a few days.
Analysis
Several different moths with similar habits are called sod webworms or lawn moths. These night-flying moths drop eggs into the grass as they fly. The eggs hatch into worms that feed on grass blades at night or on cloudy, rainy days. In the daytime the worm hides in white silky tubes in the soil. Sometimes an entire lawn is killed in a few days.
Solution Advice
Rake out all the dead grass, mow the lawn, and water thoroughly before treating. Damaged lawns may recover rapidly if the insects are controlled early.