October 23, 2026
Chinch bugs vs. sod webworms in Palm Beach County lawns
Short answer: Chinch bug damage usually shows up as yellow, then brown, patches that start in hot, sunny spots near driveways and sidewalks, and the grass dries out at the edges of the patch. Sod webworm damage looks like ragged, chewed blades and thin, scalped areas, often with small green droppings and moths flying up when you walk the lawn at dusk. A quick check at the edge of the damaged area usually tells you which one you have.
Brown patches in a St. Augustine lawn are frustrating, especially when you’re watering and the area keeps spreading. In Palm Beach County, two of the most common lawn insects behind that damage are southern chinch bugs and tropical sod webworms. They cause damage in different ways and need different approaches, so it pays to know which one you’re dealing with.
Chinch bugs at a glance
- What they are: tiny insects, black with white wings folded over the back as adults; young ones (nymphs) are reddish with a white band
- How they damage grass: they suck fluids from the grass and inject a toxin, so the grass yellows, then browns and dies
- When: most active in hot, dry weather, often spring through fall
- Where damage starts: sunny, stressed areas, especially near driveways, sidewalks and along the edges of the lawn
- What it looks like: irregular yellow-to-brown patches that spread outward; the grass looks drought-stressed even when watered
Sod webworms at a glance
- What they are: the caterpillar stage of a small, tan moth
- How they damage grass: the caterpillars chew the leaf blades, mostly at night
- When: often late summer into fall, though timing varies
- What it looks like: ragged, notched or chewed blades, thin or scalped-looking areas, and small green pellets (droppings) at the base of the grass
- Another clue: small moths flutter up from the lawn when you walk across it around dusk
Quick comparison
| Chinch bugs | Sod webworms | |
|---|---|---|
| Grass blades | Yellow to straw-brown, intact | Chewed, notched, ragged |
| Where it starts | Hot, sunny spots near pavement | Can appear anywhere, often in patches |
| Clues | Tiny black-and-white insects at the edge of damage | Green droppings, moths at dusk |
| Weather | Hot and dry | Late summer and fall |
How to check
For chinch bugs: Get down at the edge of the damaged area, where yellow grass meets green, and part the grass at the soil line. Look for tiny black-and-white adults or small reddish nymphs moving around the base of the blades.
For sod webworms: Look for chewed blades and green droppings. A soap flush can also bring caterpillars to the surface: mix a tablespoon or two of mild dish soap in a gallon of water and pour it over a small square of grass at the edge of the damage. Within a few minutes, caterpillars may come up.
If you don’t find either one, the cause may be drought, irrigation problems, fungus or something else.
What helps
- Mow at the right height and keep blades sharp. Stressed, short-cut grass is more vulnerable. Our St. Augustine dry-season guide covers mowing and watering.
- Water properly. Deep, less frequent watering keeps the lawn healthier.
- Don’t over-fertilize. Too much nitrogen can encourage chinch bugs.
- Treat what’s actually there. Applying the wrong product can waste time while the damage spreads.
How Q&L can help
Our lawn and ornamental program includes insect control, fertilization, fungus control and weed control for lawns across Palm Beach County, including Wellington, Palm Beach Gardens, Boynton Beach and Delray Beach. We inspect first to identify the cause, then treat the affected areas. See our lawn and ornamental pests page to learn more.
Frequently asked questions
Will brown grass from chinch bugs grow back?
Grass killed by chinch bugs often doesn’t recover on its own, and the area may need to be replaced once the insects are controlled. Lightly damaged grass can recover with proper care.
Can watering more fix chinch bug damage?
Watering won’t stop chinch bugs. If grass stays brown despite watering, check for insects.
Do sod webworms kill grass?
They chew the blades, which thins the lawn. Healthy St. Augustine can often recover once they’re controlled.
When should I check for lawn insects?
Any time you see new yellow or brown patches, and especially during hot, dry weather and in late summer to fall.
Do you offer complimentary lawn inspections?
Yes. Call (561) 725-5274 or book on our contact page.
Request a complimentary inspection
Book a complimentary inspection and we’ll share what we find, explain your options and recommend a plan for your home.
Request a complimentary inspection: qandlpest.com/contact-us/ · (561) 725-5274
Office hours: Mon–Fri 8:00 AM–4:00 PM.
Inspect first. Treat smart.
About the author
Michael Ringler, Q and L Pest Management. Q and L Pest Management is a family-owned pest control company based in Lantana and serving Palm Beach County since 2022.Q and L Pest Management LLC holds FDACS Pest Control Business License #JB333443. Services are performed under FDACS Certified Pest Control Operator John Park, certificate #JF320165.
Sources
- UF/IFAS Extension. St. Augustinegrass for Florida Lawns (ENH5/LH010). https://edis.ifas.ufl.edu/publication/LH010