Sod webworms feed on a variety of grasses and can do damage to your lawn. They get their name from the webs they spin as caterpillars. These webs are found along their paths as they move through the grass.
As larvae, sod webworms look greenish-brown and have dark spots along their bodies. The caterpillars, which are the stage of the worms that destroy the sod, grow to an inch in length when fully developed. When they become adults, they are small, tan moths. These moths are usually cigar-shaped when they roll their wings. They also have a snout-like protuberance and are sometimes called snout moths.
These moths fly low to the lawn when disturbed, usually by a lawnmower, and then come to rest back in the lawn. The sod webworms will feed at night and spend their days in the silk-lined burrows they create.
Sod webworms spend the winter in structures they have woven called hibernacula. These tent-like structures are just below the surface of the lawn and they protect the caterpillars from temperature extremes. When spring arrives, the sod webworms become active and feed for a short time before they become moths. Female moths will fly low to the grass and drop eggs onto the soil. In about a week, the eggs will hatch and the sod webworms will begin feeding immediately.
Look for yellow and brown patches in your lawn as a sign of sod webworm damage. As the caterpillars feed, the patches will increase in size. Normally, healthy lawns will not sustain sod webworm damage. In drought or stressful conditions, sod webworms can destroy a lawn so keep a vigilant eye on your yard. Look for webs along the grass, just below the tops of the blades. These webs will appear as tunnels made of silk.