Sod web worms are the larvae of lawn moths and are usually ½ to 1-inch long, brown or greenish with multiple black spots on their bodies. They feed on your grass, causing dead brown patches and eventual thinning during the summer. These lawn pests are dormant during the day and feed on the grass at night. The adult moth females lay their eggs on the grass blades in the evening. Eradicate sod web worms with a variety of treatments.
Remove thatch from your lawn, especially if the organic material is more than ½ inch thick, using a garden or power rake, mechanical dethatcher, or vertical mower. Mow the grass more frequently to reduce thatch buildup. Mow your lawn frequently enough that you're removing less than 1/3 of the grass's total height each time you mow.
Apply a slow-release, complete lawn fertilizer two or three times per year, according to the dosage instructions on the label. Also ensure that the grass receives about ¾ to 1 inch of water each week throughout the growing season.
Spray your grass with an insecticidal treatment that's labeled for caterpillars to get rid of sod web worms, such as neem oil or pyrethrin. Follow the directions on the label.
Apply a biological control, such as Bacillus thuringiensis (Bt) or Steinernema carpocapsae nematodes, instead of spraying an insecticide on your lawn. Bt is a selective biological pesticide organism that feeds only on certain insects, usually moth larvae.