How to identify them

Sod webworms are the larvae of small, buff-to-gray moths. The caterpillars are gray-green with dark spots and hide in the thatch during the day, coming out at night to feed. A classic sign is the adult moths: small, dingy moths that flush up in little zig-zag flights when you walk across the lawn at dusk, then dive back into the grass.

Behavior and biology in South Florida

The caterpillars chew on grass blades, leaving ragged, notched, and thinned areas that turn into irregular brown patches. Because they feed at night and shelter in the thatch by day, the damage appears seemingly out of nowhere. They favor St. Augustine and bermudagrass and are a major warm-season lawn pest in South Florida.

Populations build through the summer and often peak in late summer and fall, with multiple overlapping generations in the region’s long warm season. Small green droppings (frass) in the thatch and chewed blade edges help confirm them over other causes of browning.

Signs of an infestation

• Ragged, notched grass blades and thinning, chewed-looking turf
• Irregular brown patches that expand over days
• Small moths flushing up in zig-zag flights at dusk
• Green frass pellets and caterpillars down in the thatch

Why they are a problem

Sod webworms can chew a healthy lawn to ragged brown patches quickly during their late-season peak, and because they hide by day and feed at night, homeowners often mistake the damage for disease or drought and lose ground before treating. Repeated generations can keep pressure on the turf into the fall.

How Bugsy’s treats sod webworms

Correctly identifying webworms — versus drought, disease, or chinch bugs — is the first step, so our technicians confirm the pest by the chewed blades, frass, and larvae in the thatch. Treatment targets the active caterpillars where they feed and shelter, timed to the generations building through the warm season, so the lawn can recover and stay ahead of reinfestation.

Preventing sod webworms

• Watch for dusk moth flights and ragged blades as early warning signs
• Avoid excess nitrogen fertilization, which fuels tender growth they favor
• Keep the lawn healthy and properly watered so it recovers from feeding
• Monitor through late summer and fall when populations peak
• Confirm the cause before treating — browning has several possible culprits

At a glance

Turf pestNight feederChews grass bladesLate-season peak