Lawn guide · Insects
Armyworms: the pest that eats a lawn in a weekend
Fairway Weed Control · Updated July 2026 · Watch months in the OKC metro: August–September
Fall armyworms are the one lawn pest in Oklahoma where days genuinely matter. In outbreak years they take lawns from green to brown in 48–72 hours, and by the time damage is obvious, the easy window has closed. This page is how to catch them early — and what to do the day you find them.
What they are and why they surge
Fall armyworms are caterpillars — larvae of a moth that can't survive Oklahoma winters. Each year, moth populations rebuild in the Gulf states and ride southern winds north through summer; by August and September they're laying eggs across the OKC metro, and each egg mass hatches into dozens of larvae that feed together, moving across turf like a front line. That's the "army." Most years the pressure is scattered. Every few years — weather-dependent — it's a full outbreak, and local news covers lawns eaten to the dirt.
Identification: three checks
The caterpillar: up to about 1.5 inches, green-brown with lengthwise stripes, and the tell — an inverted "Y" marking on the head capsule. The damage pattern: browning that expands in a moving edge, often starting near field margins, fence lines, or lush irrigated areas — it looks like drought that's traveling. The flush test: mix a couple tablespoons of dish soap in a gallon of water and pour it over a square yard at the green edge of the browning. Larvae surface within minutes. Do this in early morning or evening, when they feed; midday they hide low in the canopy.
Why timing is everything
Small larvae are easy to control; large ones are hard, and large ones are also the stage doing 80% of the eating — in their final days, larvae consume more than in all previous stages combined. Practically: the day you confirm armyworms is the day treatment should happen, not the week after. Waiting for the weekend is how lawns get finished.
The aftermath: better news than it looks
Bermuda almost always comes back. Armyworms eat blades, not the crowns and runners Bermuda regrows from — with prompt treatment, water, and a feeding, most Bermuda lawns fully recover within weeks. Fescue is the vulnerable one: a bunch grass eaten low in September may need fall overseeding to recover density. And don't scalp-mow the damage or drown it midday — treat first, then support regrowth.
Where prevention fits
Our program's April surface-insect application handles early-season pressure, and during outbreak windows we monitor routes daily — a dense route means we usually see an outbreak arriving on your street before you do. Program customers get outbreak retreatment under the program; if a wave is active when you read this, call or text (405) 437-4929 — outbreak scheduling runs first-come by route.