Bermuda Grass Guide

Fall Armyworms in Bermuda Grass: How to Tell and When to Treat

Early damage can look like plain drought stress, but fall armyworms can strip a Bermuda lawn in days once a population takes hold — and late August is the peak of the window for it in the Transition Zone.

Reviewed by Dave, Founder, LawnCoach

If you're seeing chewed, ragged grass blades or a brown patch that seems to be spreading day to day in your Bermuda lawn, fall armyworms are a real possibility right now — Transition Zone pressure peaks specifically from mid-August through mid-September, and they can strip a lawn bare within days once a population takes hold.

What armyworm damage looks like

Early damage can look almost identical to plain drought stress — thinned, slightly off-color grass. The real giveaway is the blades themselves, not just the color: look closely for chewed, ragged edges or a scalped look where the green tissue has been eaten away, and watch for birds actively feeding in the area, which is often the first sign something's there before you'd notice it yourself. Armyworms feed above ground and are most visible early morning and late afternoon — in a heavy infestation, a patch can visibly look like it's moving as they forage.

Why this matters

Armyworms feed above ground and can strip a lawn in days once a population takes hold — unlike grubs, which feed on roots out of sight and do damage more slowly. Checking during peak pressure instead of waiting for it to look obviously bad is what keeps a bad week from becoming a bare lawn.

Confirming it, and when to treat

A soap flush confirms it in minutes: mix 2 tablespoons of dish soap per gallon of water, pour it over a 3x3 foot area at the edge of the damage, and watch for 5–10 minutes — caterpillars will surface if they're there. Once confirmed, a fast-acting curative insecticide is what actually stops it; a season-long preventive product needs to go down in spring, before populations build, and won't act fast enough once damage is already visible. Whichever curative product you use, avoid watering (or counting on rain) within 24 hours of applying it — that washes away the product before it can work.

What to expect

Damage can appear and spread within days once a population takes hold, so check every few days through mid-September rather than just once. Treated areas should stop showing new damage within a couple of weeks, but existing brown patches won't green back up on their own — those spots may need overseeding or patching once the pest pressure is resolved.

Checking your lawn and finding loose turf that pulls up like carpet, with no chewed blades or birds around? That's more likely grubs — a below-ground pest with a different tell and a different fix.

What does fall armyworm damage look like in Bermuda grass?

Chewed, ragged grass blades or a scalped-looking patch, often with birds actively feeding in the area. Damage can visibly spread within days once a population takes hold.

How is armyworm damage different from drought stress or grubs?

Early on, it can look just like drought stress — the tell is the blades, not the color: chewed and ragged, not just faded. It's different from grubs specifically because armyworms feed above ground on the blades and can strip a lawn in days, while grubs feed on roots below ground and the giveaway there is turf pulling up loose with no roots attached.

How do I confirm armyworms before treating?

A soap flush: mix 2 tablespoons of dish soap per gallon of water, pour it over a 3x3 foot area at the edge of the damage, and watch for 5–10 minutes. Caterpillars will surface if they're present.

When is armyworm pressure highest, and how often should I check?

Transition Zone pressure peaks from mid-August through mid-September. Check every few days during that window rather than just once, since damage can spread within days once a population takes hold.

Sourced from Clemson HGIC and Virginia Tech Extension.

Know exactly when to check — for your zone

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