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How to Kill Sod Webworms

By Athena Hessong

Sod webworms are the larvae of lawn moths. These pests eat grass and dig tunnels in the soil. Their tunnels are lined with silk similar to a spider's web, which gives the larvae their name. The grass above their tunnels browns and dies when the webworms come out of the tunnels to eat the grass. Significant infestations of sod webworms can kill large patches of your lawn; killing the webworms will help to save your lawn.

Water the affected area to a depth of 1/2 inch two days before applying chemical agents.

Follow the label instructions on your pest control product, and apply it only to the areas of damaged lawn.

Water the pesticide into your lawn with 1/2 inch of water.

Mow the lawn to 1 1/2 inches high.

Keep your lawn watered to a depth of 1/2 inch for one week to improve the penetration of the pesticide.


Things You Will Need

  • Liquid dish soap
  • Turfgrass pesticide for sod webworms
  • Lawn mower


  • Verify that you have sod webworms before starting treatment. Combine 2 tbsp. liquid dish soap with 2 gallons of water. Evenly pour the soapy water over a 1-square-yard area of your lawn where you notice 1/4- to 3-inch areas of brown in the lawn. Wait two to three minutes for the webworms to come to the surface. Count them and consider treating your lawn if you see 10 or more larvae.
  • Look for any of the follow in your pesticide as the active ingredient for effective treatment of sod webworms: acephate, beta-cyfluthrin, trichlorfon, carbaryl, deltamethrin, chlorpyrifos, lambda-cyhalothrin or bifenthrin.