Adult sod webworms, called lawn moths, are typical snout moths: they have sensory appendages called labial palps that extend in front of the head. The moth holds its wings close to and over its body at rest, giving it a slender appearance. When disturbed, the moth makes a short flight close to the grass. At night, these moths drop their eggs indiscriminately on to turf.
The creamy larvae of the sod webworms have a distinctive double row of brown or black spots down their backs, located at the base of long bristles. The Lucerne moth larva is somewhat larger than the other sod webworm larvae. During the day larvae reside in silk-lined burrows, writhing when disturbed. At night they emerge to feed.
Sod webworm larvae are leaf skeletonizers. As the larva mature they will notch or cut off leaf blades and pull them into the burrow. Heavily infested turf quickly appears moth eaten, with irregular patches of brown grass or bare areas.