Brown irregular spots and later ragged uneven patches of grass are the first indications of lawn damage. The grass on the edge of dead patches is short or uneven from the feeding activities of the larvae. A search for the larvae should concentrate in the thatch of the margins of dead patches since this is where active feeding occurs. If the infestation is heavy, large areas of grass may be damaged severely or destroyed in only a few days. Sod webworm moths do not feed on lawns but are frequently observed flying over the lawn on calm evenings as they move about to lay eggs.
Sod webworms have a preference for newly seeded, thick lawns.
They prefer bentgrass, bluegrass, fescue and timothy, as well as pasture and field grasses. They fold their wings tightly over their bodies at rest and have a prominent projection on the front of the head that forms a distinctive snout. At rest on the grass, they resemble pieces of a wooden match stick attached to a grass blade. The front wings are triangular, narrow and have a distinctive wing scale pattern. The front wing scale pattern may have a distinctive silver, white or black longitudinal streak.