Sod webworms spend the winter as larvae. Living in silken tunnels just below the soil line, larvae become active in the spring and feed on roots, stems and blades of grass. Larvae pupate in underground cocoons made of silk, soil and bits of plants. About ten days to two weeks later the moths emerge. The moths live a few days and feed only on dew.
Moths are most active at dusk.
Females lay eggs randomly over the grass. The eggs hatch in about a week, and young larvae begin to feed. In feeding, the larvae cut grass blades just above thatch line, pull them into their tunnels and feed there. Injury appears as small brown patches of closely mowed grass. When there are many larvae present, these patches run together and form large, irregular dead patches.