NC State Extension Publications

Description and Biology

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Moths of the fall armyworm, Spodoptera frugiperda, invade North Carolina each year from the Gulf Coast states where they overwinter as pupae. The moths usually arrive in mid July and their caterpillars become more and more abundant as the weeks go by, hence the name fall armyworm. Each moth can lay as many as 1,000 eggs on flowers, turfgrasses, and other crops. The moth has a wingspan of about 1½ inches. The hind wings are white with buff edges; the front wings are dark gray and mottled with lighter and darker splotches. Each forewing has a noticeable whitish spot near the extreme tip. Fall armyworm eggs are minute, light gray and are laid in clusters covered with grayish, fuzzy scales from the body of the moth. The eggs become very dark just before hatching. This green, brown, or almost black caterpillar and resembles the corn earworm in shape and markings. However, the fall armyworm has a distinct, pale, inverted “Y” on the front of its head. Each side of its body has a black stripe and each abdominal segment has four black dots on top. After feeding for 2 to 3 weeks, armyworms dig about an inch into the ground to pupate. The pupa is reddish-brown and darkens to almost black as it matures. Within 2 weeks, a new generation of moths emerges and may fly several miles before laying eggs. Dry weather in late summer may cause this insect to move from field crops and pastures to landscaped areas. Several generations occur each year in North Carolina.

Fall armyworm

Fall armyworms tend to attack flowers in late summer and fall.

Fall armyworms typically pupa

Fall armyworms typically pupate in soil.

Fall armyworm moth

Fall armyworm moths invade North Carolina from the Gulf Coast.

hind wings of fall armyworm moth

The hind wings of fall armyworm moths are pale with darker borders.

Fall armyworm moths lay eggs

Fall armyworm moths lay eggs in groups and cover them with scales.

Host Plants

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The fall armyworm has a wide host range but prefers grasses. Fall armyworms may migrate in large “armies” and invade landscapes consuming all above-ground parts of herbaceous ornamentals. They seem to prefer feeding on the flowers of African violet, chrysanthemums, and other ornamentals. They tend to feed on the foliage of ornamental grasses.

Residential Recommendations

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Because these caterpillars have an enormous host range including weeds that are never sprayed, fall armyworms are not likely to have developed resistance to insecticides. Unfortunately, fall armyworms tend to infest the flowers of ornamental plants, which presents a dilemma: applying an insecticide to flowers may harm bees, butterflies, and other pollinators. Fortunately, fall armyworms are not a really common pest of flowers so hand picking or dislodging and trampling underfoot may provide sufficient control. Foliage may be sprayed those insecticides labeled for landscape use to protect the foliage of plants from fall armyworms.

References

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For assistance with a specific problem, contact your local Cooperative Extension Center.

This Factsheet has not been peer reviewed.

Author

Professor Emeritus
Entomology and Plant Pathology

Publication date: Feb. 13, 2017
Revised: Sept. 16, 2019

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