Here are several species of caterpillars called sod webworms that can be highly destructive pests of U.S. lawns. They may also become important pests of grass covered parks, cemeteries, golf courses. They have even been noted to cause damage in small grain crops such as corn, wheat and oats. Damage to grass is caused by the feeding of the larval or "worm" stage. The adult moth does not cause damage to turf, other plants or clothing. The damage caused by sod webworms may first appear in early spring. The damage shows up as small dead patches of grass among the normally growing grass. The summer generation may cause general turf thinning or even irregular dead patches in late June into early August. Sod webworms prefer sunny areas and the larvae are often found on south facing, steep slopes and banks, where it is hot and dry. Heavily shaded turf is seldom attacked by the larvae.

The most severe damage usually shows up in July and August when the temperature is hot and the grass is not growing vigorously. In fact, most sod webworm damage is mistaken for heat and drought stress. Sod webworm-damaged lawns may recover slowly, without irrigation and light fertilizations. These thin turf areas allow weeds to establish in the lawn making it unsightly. Sod webworms appear to feed on all the common turfgrass used throughout the U.S. However, common Kentucky bluegrass, perennial ryegrass and fine fescues are the ones showing damage the most. However, improved perennial ryegrasses with endophytes are highly resistant to sod webworms. Likewise, tall fescue, though often attacked, usually out grows the damage. On golf courses, bentgrasses are commonly attacked.