Warm-season grass
St. Augustine Grass: Chinch Bugs
Worried about chinch bugs on your St. Augustine grass lawn? Spreading brown in the hottest, driest part of the lawn. This guide takes the general diagnosis and tunes it for St. Augustine grass — the signs to look for, what to do first, and how a warm-season lawn recovers — kept safety-first, with the product label as the final word.
What this means for St. Augustine grass
St. Augustine grass is a warm-season grass at its peak in summer, so when it browns or thins the cause is usually a specific pest, disease, or drought — not the grass simply giving out. That makes identifying the culprit the whole game: fix the actual cause and a healthy stand normally bounces back.
A known weak spot for St. Augustine grass: Prone to chinch bugs and gray leaf spot.
How to tell on a St. Augustine grass lawn
- Yellow-then-brown patches in the hottest, sunniest, driest part of the lawn.
- Damage that keeps expanding despite regular watering — unlike plain drought, which responds to water.
- Tiny black-and-white insects (and smaller red nymphs) when you part the grass at a patch edge.
- Worst along sidewalks, driveways, and south-facing edges where it's hottest.
What to do
- Step 1
Part the grass and look
At the edge of a spreading patch — where damaged meets healthy — part the grass to the soil and watch for the fast-moving black-and-white adults and reddish nymphs. Confirming them is what separates chinch bugs from simple heat stress.
- Step 2
Use water to tell them apart
Plain drought greens back up after a deep soak; chinch-bug damage keeps spreading anyway. If watering isn't stopping it and you find the insects, it's chinch bugs.
- Step 3
Treat only what's confirmed, with a labeled product
If you confirm chinch bugs, choose an insecticide labeled both for chinch bugs and for your grass — some products injure St. Augustine — and treat the affected area. Reseed or plug killed spots once they're gone.
Always read and follow the product label — it is the legal authority on rates, timing, and safety. These windows are regional estimates, not a prescription; defer to the label and your local extension office.
How St. Augustine grass recovers
St. Augustine grass spreads and self-repairs, so once the cause is handled, small thinned or damaged areas usually fill back in on their own with steady watering and time — you rarely need to reseed.
Safety first on St. Augustine grass
Several weed killers that are fine on other lawns will damage St. Augustine — confirm the label lists it by name before spraying. Keep nitrogen at or below ~1 lb per 1,000 sq ft per feeding. Always read and follow the product label — it is the legal authority on rates, timing, and safety. These windows are regional estimates, not a prescription; defer to the label and your local extension office.
Preventing it next season
Mow high, water deeply, and avoid excess nitrogen and thatch, which chinch bugs favor. A healthy, properly watered lawn is far more resistant, and catching them early keeps the damage small.