Pest profile

Yellowstriped Armyworm

Spodoptera ornithogalli · Lepidoptera: Noctuidae[2]

Yellowstriped armyworm caterpillars feed on dozens of vegetables and also chew tomato fruit.[1]

Yellowstriped armyworm caterpillar, dark with black triangles and a yellow stripe along each side, on gravel
Yellowstriped armyworm caterpillar, dark with black triangles and a yellow stripe along each side, on gravel. (c) Elizabeth Green, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Mature larvae, up to about 1 1/2 inches, have black triangles along each side with a distinct yellow or white line below.[1]
  • Moths have brownish-gray forewings with whitish diagonal bands and white hind wings with a narrow brown edge.[1]

Where it lives

It's common in the eastern U.S. west to the Rocky Mountains, but as a pest it's limited mainly to the Southeast.[1]

US map: public records from 38 states since 1990 (GBIF).

Biology and life cycle

There are three to four generations a year, about 40 days from egg to adult.[1]

Young larvae feed in groups, then spread out, sometimes riding the wind on silk strands.[1]

Damage and signs

  • Small larvae skeletonize leaves; older ones eat whole leaves and feed on tomato fruit.[1]
  • Hosts include bean, cabbage, cucumber, lettuce, onion, potato, sweet potato, tomato and watermelon.[1]

Health risk

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

Control

Prevention

Crops near weedy rangeland or alfalfa are more prone to injury.[1]

Biological control

Bacillus thuringiensis kills armyworms but should be applied while larvae are young.[1]

Pesticides

Foliar insecticides prevent injury, and larvae eat bran baits containing insecticide.[1]

Common questions

What's the striped caterpillar eating my tomatoes?
Possibly the yellowstriped armyworm, which feeds on tomato fruit.[1]
Does Bt work on armyworms?
Yes, if applied when larvae are young; they get harder to control as they mature.[1]

Sources

  1. University of Florida IFAS Extension (Featured Creatures), “Yellowstriped Armyworm, Spodoptera ornithogalli (EENY-216).” edis.ifas.ufl.edu/publication/IN373 (accessed 2026-10-06)
  2. iNaturalist, “Spodoptera ornithogalli taxon page (order and family).” www.inaturalist.org/taxa/118930 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.