Text adapted from Turfgrass Pest Management: A Guide to Major Turfgrass Pests in Oklahoma. Oklahoma Cooperative Extension Service.

INSECT AND DESCRIPTION: Sod webworms, Crambus spp. Larvae slender, grayish, blackspotted caterpillars about 3/4 inch long when full grown, rather sluggish in their activity. Moths whitish or buff-colored. Wing span slightly over 1 inch. One species with white or silver stripe along margin of forewing, others without stripe. Wings folded close to body when at rest giving slender appearance.

LIFE HISTORY AND HABITS: Moths hide during day in grass and shrubbery; fly over grass at dusk. Eggs are laid on the leaves and crown. Larve hatch in a few days and begin to feed. They feed at night and hide during the day in shelters constructed of bits of grass and debris. Moths begin flying in April or May in warm areas and breeding continues through October. There may be 3 or 4 generations per year with broods overlapping.

SUSCEPTIBLE PLANTS: All grasses. Bent and blue grasses most susceptible to injury, especially new lawns.

DAMAGE CAUSED: Larvae feed on grass blades growing tips and greener portions of crown, but not on the roots. Damaged areas appear as scattered irregular, brown patches in turf.

METHOD OF DETECTION: Pyrethrum test. Treat when 15 or more larvae are found per square yard. Preventive treatments are suggested for newly planted lawns.

Figure 2. -- "Sod webworm moth", North Carolina Cooperative Extension Service