Warm-season grass
Bahiagrass: Armyworms
Worried about armyworms on your Bahiagrass lawn? Green to brown in days — the late-summer caterpillar that eats lawns. This guide takes the general diagnosis and tunes it for Bahiagrass — 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 Bahiagrass
Bahiagrass 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.
How to tell on a Bahiagrass lawn
- Large areas thinning or browning very fast — sometimes overnight — often spreading like a moving front.
- Up close, the blades are chewed, ragged, and see-through rather than evenly drought-browned.
- Lots of birds suddenly working the lawn — they're eating the caterpillars.
- Green-to-brown striped caterpillars (up to ~1.5") with a pale inverted 'Y' on the head, most active at dawn and dusk.
What to do
- Step 1
Confirm with a soapy-water flush
Before you do anything, confirm it: mix a couple of tablespoons of dish soap into a gallon of water and pour it over a square yard where green meets brown. Armyworms surface within a few minutes if they're there. Check early morning or evening, when they feed — they hide near the soil in the heat of the day.
- Step 2
Treat a confirmed, active infestation
If you find an active infestation, choose an insecticide labeled for armyworms and apply it in the late afternoon or evening, when the caterpillars are feeding — smaller, younger larvae are far easier to control. Treat the damaged area and a buffer around it.
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.
- Step 3
Water to recover — and feed only when it's growing
Once the worms are gone, keep the lawn watered so it can rebuild. If it's actively growing — not heat- or drought-stressed, and not a cool-season lawn in summer — a light feeding helps it bounce back; otherwise hold the fertilizer and let water do the work. Bermuda and other spreading grasses usually green back up from the crowns within a couple of weeks; bunch-type lawns like tall fescue may need bare spots reseeded in the fall.
Never exceed ~1 lb of nitrogen per 1,000 sq ft in a feeding, and never feed a heat- or drought-stressed lawn. 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 Bahiagrass recovers
Bahiagrass 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 Bahiagrass
Some herbicides used on other Southern lawns are meant to KILL bahiagrass — read the label carefully and confirm it is safe for bahiagrass first. Keep nitrogen at or below ~1 lb per 1,000 sq ft per feeding, and use iron, not extra nitrogen, for high-pH yellowing. 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
There's no reliable preventer the way there is for grubs — armyworms blow in on late-summer moth flights — so the key is scouting. Watch for sudden bird activity or a neighbor's lawn going brown in late summer, and check early: small larvae caught early are far easier to stop than a full-grown army.