Common Name: Yellowstriped armyworm
Scientific Name: Spodoptera ornithogalli (Guenée)
Description: Caterpillars are up to 2 inches long and vary in color from green when small to almost black when large. They have two cream yellow to orangish stripes along the back, and a prominent dark spot on the sides of the fourth body segment behind the head (the first legless abdominal segment). Partially grown larvae appear to have pairs of triangular dark markings along the back of each body segment inside of the light-colored stripes. Adult moths have a wing span of 1-1/2 to 1-3/4 inches.
Armyworm caterpillars can be identified by examining the front of the head capsule. They have light-colored markings along the seams (sutures) of the “face” that appear as an upside down Y.
Other common species of armyworms in Texas include:
1) the “true” armyworm, Pseudaletia unipuncta (Haworth) that varies in color from brown to black, usually with lighter colored stripes along the body;
2) the beet armyworm, Spodoptera exigua (Hübner) which is generally green with or without stripes, but always with small distinct dark spots on the sides of the second body segment behind the head;
3) the fall armyworm, Spodoptera frugiperda (J. E. Smith) which varies in color but usually with prominent body strips and small round shiny black areas around the bases of prominent body hairs on each body segment; and
4) the variegated cutworm, Peridroma saucia (Hübner), which varies greatly in color, but usually with a series of whitish markings at the back margin of the top of four to seven of the body segments.
Life Cycle: Adult moths lay clusters of eggs on host plants and then covers them with scales from her body. Small (1/8 inch) caterpillars hatch from eggs in about 6 days. Caterpillars develop through several molts to increasingly larger stages (instars) over a period of about 20 days until they pupate in the soil for 14 days or overwinter. Adult moths emerge from the pupae. Several generations can be produced each year, each being completed in 35 to 45 days to several months depending on temperature, food and environmental factors.
Habitat and Food Source(s): Caterpillars have chewing mouthparts. Adults have siphoning mouths. This is one of the most common caterpillars encountered in the vegetable garden, feeding on leaves during the day. Caterpillars strip foliage from one plant and then move on to the next available food plant. Although certain plants are preferred hosts, such as cotton, tomatoes, chrysanthemums, forages and turfgrasses, larvae will feed on a large number of plants. In cotton, larvae also tunnel into developing cotton bolls.
Pest Status: Caterpillars feed on plants; medically harmless.
Literature: Bohmfalk et al. 1982. Jackman 1981. Metcalf et al. 1962. Rings & Musik 1976.