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 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.
Bluegrasses and bent grasses often suffer the most damage, while perennial ryegrasses and turf-type tall fescues infected with endophytes (symbiotic fungi) are more resistant.
First instar sod webworm larvae are leaf skeletonizers. Later instars notch or cut off leaf blades and pull them into the burrow. Heavily infested turf (more than 100/sq yd) quickly appears moth eaten, with irregular patches of brown grass or bare areas. Significant damage can occur on drought-affected bluegrass and on bentgrass green and tee areas. Lucerne moths are primarily a problem where clover and dichondra are mixed with turfgrass.