Fall Armyworm

Spodoptera frugiperda

Fall Armyworm is a species-level migratory armyworm associated with corn, sorghum, turfgrass, pasture grasses, rice, peanuts, vegetables, and many field crops. Windowpaning by small larvae progresses to ragged whorl feeding, abundant frass, clipped turf, and injury to ears or reproductive structures. In turf, damage can expand rapidly across warm-season grasses. Risk changes with larval size, crop stage, and concealment. Pass-specific distinction 1: Fall Armyworm.

Identification

Larvae have a pale inverted Y on the head and four dark dorsal spots arranged as a square on the next-to-last abdominal segment. Young larvae often feed in groups; older larvae become solitary and hide in whorls. Inspect whorls, grassy edges, and turf at dawn for egg masses, small larvae, frass, and fresh chewing. Pheromone traps indicate moth flights but do not substitute for larval counts.

Symptoms / Signs

Windowpaning by small larvae progresses to ragged whorl feeding, abundant frass, clipped turf, and injury to ears or reproductive structures. In turf, damage can expand rapidly across warm-season grasses. Fresh injury carries live larvae, new frass, or moist feeding margins.

Life Cycle / Process

Eggs occur in fuzzy masses covered with abdominal scales. Larvae pass through several instars and pupate in soil. Florida can support local survival, while strong-flying moths also disperse long distances. The larva is the damaging stage. Act before larvae enlarge, bore, or complete protective shelters.

Prevention

Inspect incoming plants and nearby reservoir hosts named for this species. Operational focus: Fall Armyworm.

Management / Control

Target small larvae before they burrow deep into whorls or become large. Conserve predators and parasitoids, use Bt or virus products where labeled, and rotate modes of action because resistance is common.

Procedure Steps

1. Inspect corn, sorghum, turfgrass, pasture grasses, rice, peanuts, vegetables, and many field crops for eggs, small larvae, and the freshest feeding pattern. 2. Confirm the species from larval characters, host, and behavior before applying thresholds. 3. Record larval size, injury, and natural enemies on a repeatable crop-specific sample. 4. Use Bt, virus, or a selective labeled product while larvae are small and exposed. 5. Reinspect the same host stage and distinguish new injury from old feeding. Operational focus: Fall Armyworm.

Safety Notes

Protect food, seed, packaging, workers, and Myco-Patrons during inspection and treatment. Use tamper-resistant placements where baits or traps are necessary, and keep pesticides off food-contact surfaces. Structural or termite work may require a licensed Florida pest-control operator.