Sod Webworms
Several species of caterpillars are called sod webworms and in the larval stage they can be highly destructive pests of lawns. The caterpillars live in silk-lined tunnels constructed in the thatch near the soil surface. They chew grass blades off just above the thatch line, and are mainly active at night. The adults of sod webworms are often called lawn moths because they fly in a jerky zigzag pattern a few feet above the lawn.
Most sod webworm larvae are under one inch in length. They have dark shiny heads and vary in color from greenish to beige, brown or gray. They have four parallel rows of dark spots along the length of their abdomen.
Sod webworms adults (moths) are 1/2 to 3/4 inch long, buff-colored or grayish-brown. At rest they fold their wings closely against their bodies, giving them a very narrow appearance.
In thick, green turf, damage appears as small brown patches. When many larvae are present the patches run together and form large irregular, thin and brown areas.
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Identification and Control Information
- Turfgrass Science: Sod Webworm (PDF)—Michigan State University
- Entomological Notes: Sod Webworms in Home Lawns (PDF)—Penn State Cooperative Extension
- Utah Pests Fact Sheet: Sod Webworms (PDF)—Utah State University Extension
[Photos, left to right: University of California IPM Program; Ontario Ministry of Agriculture, Food and Rural Affairs; unknown]