Clemson Extension shares tips for identifying fall armyworms
August 19, 2026
Late summer is prime season for fall armyworms in South Carolina, and Clemson Cooperative Extension is helping producers and homeowners learn to spot them before they do serious damage.
The Extension Service’s livestock and forages team shared identification tips on social media Aug. 10, encouraging anyone with questions to contact their local livestock and forages agent.
The easiest way to confirm the pest is to look closely at the caterpillar’s head. A fully grown fall armyworm larva carries an upside-down Y shape on its head capsule, along with three white stripes running just behind the head. A second marker is found at the opposite end. Four dark dots form a square pattern on the last segment of the abdomen.
The adult stage is a small moth with mottled gray and brown front wings and pale hind wings. Moths move into the Southeast in late spring, and the region can see five or more generations in a single year.
Fall armyworms do not survive South Carolina winters. They overwinter in Florida, south Georgia and points farther south, then ride air currents north each year. Hot, dry summers favor their development, and populations typically peak in late summer and early fall.
The caterpillars feed on a wide range of forage crops, including bahiagrass, pearl millet, tall fescue and sorghum-sudan hybrids, but the heaviest damage usually shows up in lush, well-fertilized bermudagrass. Home lawns are also at risk.
Damage often goes unnoticed at first because the eggs and young larvae are so small. Once the caterpillars reach full size, they can strip a hayfield or pasture in a matter of days, leaving ragged leaves, bare stems and brown patches that can be mistaken for drought stress.
Scouting is the best defense. Producers are encouraged to walk fields regularly and check early in the morning and late in the afternoon, when the caterpillars are most active. A sweep net can help detect low populations before feeding damage becomes obvious.
Anyone who suspects fall armyworms in a pasture, hayfield or lawn can reach out to their local Clemson Extension office for identification help and current treatment recommendations.
