Sod Webworms
Egg - The tiny egg is pale and oblong.
Larva - The apparently legless larva is pinkish-white, yellowish, or light brown. When full-grown, it is 16 to 19 mm long. Its thick body is marked by coarse hairs and paired dorsal and lateral spots on each segment. The head is yellowish-brown, brown, or black.
Pupa - The pupa is reddish-brown, immobile, and about 13 mm long.
Host Plants - Sod webworms feed on corn, tobacco, bluegrass, timothy, pasture and field grasses, some clovers, and lawn and golf course grasses.
Damage -Sod webworms cause two kinds of damage: that done to cultivated crops (such as corn and tobacco); and that occurring in pastures, lawns, grassland, meadows, and golf courses. In corn, the larvae feed just underground on the stem, often nearly severing it. This type of damage usually occurs in the spring when plants are small and most vulnerable to stem damage (see Corn/Sorghum Sod Webworm Note). In grasses, they either cut off the blades at ground level and pull them into the tunnels, or they skeletonize the plants, causing characteristic brown spots in normally green lawns. The latter type of injury is more common in the summer. Several other insects, such as cutworms, wireworms, and billbugs, are often credited with webworm damage in turf.
Life History - Webworms pass the winter in silk-lined nests several centimeters deep in the soil. Usually, they overwinter among the roots of weeds or grasses. In spring, the larvae become active and feed at night on the upper root systems, stems, and blades of grass. They also construct protective silken nests in which they feed and mature. About June first, larvae construct cocoons of silk, plant debris, and soil particles, and pupate within them. In a week or two, the adult moths emerge from the cocoons, move up the silken tunnels, and mate. The moths, which are weak, erratic fliers, live only a few days and feed on dew. They are most active at dusk, resting during the day near the ground in grass. The eggs, indiscriminately dropped over the grass, hatch in a week or 10 days. The young larvae then feed and start construction of the silken tunnels, which are reinforced with dirt and grass. There are one to three generations per year, depending upon the species.