How to Get Rid of Sod Web Worms

Lawn pests build up as the grass greens in spring and keep going through the summer. Walk the lawn weekly from late spring on, and watch for small moths and thinning patches so you catch trouble early.

Confirming Webworms and Helping the Lawn Recover

Brown patches can come from drought, chinch bugs, disease or webworms, so confirm the cause first.

• Look closely at the blades. Webworm damage shows chewed, notched or ragged leaf edges, and the grass can look freshly scalped. Chinch bug damage turns grass yellow and dry without chewing.
• Do a soapy water flush. Mix a tablespoon or two of liquid dish soap into a gallon of water and pour it over a small area at the edge of the damage. Caterpillars in the thatch wriggle to the surface within a few minutes.
• Check after dark with a flashlight, when larvae come up to feed.

Cultural habits make a big difference:

• Mow at the recommended height for your grass type rather than scalping it.
• Avoid heavy doses of quick-release nitrogen fertilizer, which push the lush growth webworms favor.
• Water deeply and less often instead of with daily light sprinklings.

Common mistakes include treating the whole yard on a guess, using a chinch bug product when the problem is caterpillars, and applying anything in the morning when larvae are hidden in the thatch. Treatments are usually timed for late afternoon or evening, just before larvae feed. Because webworms chew leaves rather than roots or runners, lightly damaged lawns often grow back once feeding stops.

A professional lawn pest visit generally involves confirming the pest, treating only the active areas at the right time of day, and checking back to make sure feeding has stopped. Identification tips are on our sod webworm page.