Sod webworms are surface feeders. Look for young caterpillars with black heads. Adults are up to 3/4 inch long and brown to green with dark spots. Adult moths have snout-like mouthparts.
Signs of feeding include chewed grass blades and fecal pellets.
To monitor sod webworms, mix 2 to 4 tablespoons of dishwashing soap in a gallon of water. Sprinkle over about 1 square yard of turf. Webworms will come to the surface in about 10 minutes. Flush the area with fresh water to prevent injuring turf.
Prevent damage by planting endophytic enhanced varieties of perennial ryegrass and fine leaf and tall fescues.