Sod Webworms

Order/Family: Lepidoptera/Pyralidae

Description:

  • Adults moths are dull colored. The wingspan is 3/4- to 1-inch long and colors vary from white, gray to tan. The wings are rolled around the body, giving them a tube-like appearance. They have two snout-like projections extending from the front of the head.
  • When full grown, larvae are 3/4-inch long.
  • Sod webworm larvae are tan, brown, gray or green depending on the species. Most species have dark spots and stout hairs on their bodies.

 

Biology and Habits:

  • The female flies over the grass at night dropping the eggs singly into the turf. The eggs are not sticky therefore they tend to settle in the thatch.
  • Over a two-week period the females deposit approximately 60 eggs per night.
  • The eggs hatch within a week and the larvae mature in 4 to 7. The life cycle can be completed in 6 to 10 weeks.
  • They overwinter as mid-sized larvae in silken cocoons.
  • There are two to three generations per year.
  • The immature larvae feed on the surface of the leaves. As the larvae mature they drop down into the thatch or soil where they make a tube lined with silk.
  • The adult moths rest in the grass during the day, are erratic fliers, and are active at night.

 

Turf Attacked:

  • Kentucky bluegrass, perennial rye, fescue, St. Augustine, and creeping bent grass.

 

Damage:

  • Only the larvae cause turf damage.
  • The immature larvae feed on the surface tissues of the leaves.
  • Mature larvae chew the grass leaves off at the base and eat them in their tunnels, exposing grass crowns.
  • Bits of uneaten grass and tiny green colored frass around the opening of the tunnel is indicative of infestation.
  • Damage begins with thinning and as it progresses the grass turns brown and is closely cropped.
  • Damage in combination with stress can kill the grass.