Sod webworms overwinter as immature larvae in silk-lined chambers in the thatch layer. As temperatures begin to warm in the spring, larvae become active and resume feeding on turf grass blades at night. During the day, larvae will seek refuge in the thatch layer.

Sod webworms overwinter as immature larvae in silk-lined chambers in the thatch layer. As temperatures begin to warm in the spring, larvae become active and resume feeding on turf grass blades at night. During the day, larvae will seek refuge in the thatch layer. Larvae are more obvious and curl into a ball when disturbed.

Adults are also nocturnal and can be seen flying low over turf grass and feeding on plant dew. Mated fe­males will drop eggs over the turf grass;

One way to flush larvae from the thatch layer is to pour soapy water (2 tablespoons liquid dishwashing detergent into 2 gallons of water) over a 1ft2 area on the turf grass and watch for larvae to surface.

Caterpillars feed during the night on turf grasses. Injured grass blades initially appear notched and ragged as tissues are removed from the edges until the entire leaf is consumed. Injured turf is usually spotty within a lawn, but damaged areas enlarge as caterpillars migrate in search of more food. Heavily injured turf grass may die but usually recovers. St. Augustine grass recovers more slowly than Bermuda grass.

Sod webworms prefer to feed on turf grass, being the ideal food source. Larvae are the damaging life stage and clip turf grass blades off just above the crown. Initially, sod webworm damage begins as a general thinning to a small area, followed by the presence of obvious brown patches. Severe infestations can cause large irregular patches throughout a lawn. Because sod webworms are feeding on aboveground plant tissue, the roots remain intact.