Southern Armyworm

How to identify it

• Larvae grow to about 1 1/3 inches, green or blackish green with a light brown head and a pale side stripe broken by a dark spot near the front.^[1]
• Moths have gray and brown forewings with dark markings and white hind wings.^[1]

Where it lives

Native to the American tropics, it occurs mainly in the southeastern U.S., west to Kansas and New Mexico.^[1]

US map: public records from 13 states since 1990 (GBIF). View the map

Biology and life cycle

Florida has about four generations a year, each taking 30 to 40 days.^[1]

Larvae usually sit under leaves and are most active at night.^[1]

Damage and signs

• Hosts include tomato, pepper, eggplant, sweet potato, beet, cabbage, okra, watermelon, citrus and flowers.^[1]

Health risk

It feeds on plants; UF/IFAS mentions no risk to people.^[1]

Control

Biological control

Several parasitic wasps attack it.^[1]

Pesticides

Foliar insecticides work best on small larvae; larvae are hard to control with botanical insecticides.^[1]

Common questions

What's boring into my tomatoes in Florida?

Southern armyworm larvae often bore into tomato fruit.^[1]

When should armyworms be treated?

When larvae are small; they're much harder to control as they grow.^[1]

Sources

1. University of Florida IFAS Extension (Featured Creatures), “Southern Armyworm, Spodoptera eridania (EENY-106).” edis.ifas.ufl.edu/publication/IN263 (accessed 2026-10-06)
2. iNaturalist, “Spodoptera eridania taxon page (order and family).” www.inaturalist.org/taxa/231424 (accessed 2026-10-06)