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United States Department of Agriculture

Agricultural Research Service

Beet / Fall Armyworm
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The Beet Armyworm, Spodoptera exigua, is a pest in the southern states and feeds on cotton, corn, soybean, tobacco, alfalfa, sugar beets, pepper, tomatoes, potatoes, onions, peas, and citrus. The early silk larva damage the young terminal growth, while later larva feed on foliage and other plant parts.

Characteristics
The larva is green or black with a dark head, five pairs of prolegs, and three lightly colored stripes running the length of the body. A small black spot on each side of the second segment behind the head usually becomes visible. Mature larva are about 1 inch long with prominent lateral stripes. The body has hairs with a black spot on the second thorax segment. The moth's wingspan is about 1 inch with gray or brown coloring and has a pale spot near the center. The hind wings are white with dark lines.

Life Cycle
The pupae overwinter in the soil. Spring females lay several mass clusters of 50 to 100 eggs and up to 600 eggs in a week. Eggs hatch in 2-3 days, spin loose webs, and spread to different parts of the plant to feed for 1-3 weeks before pupating. Moths emerge in about 1 week and live for 4-10 days. The entire life cycle is about 4-5 weeks with several generations per year.


Beet armyworm Beet armyworm moth




The Fall Armyworm, Spodoptera frugiperda, has migrated throughout the eastern and central United States and feeds on corn, cotton, soybeans, alfalfa, beans, peanuts, potatoes, turnips, tomatoes, cabbage, cucumbers, and tobacco. They damage corn crops by eating foliage, the whorl, the ears, and the developing fruiting forms. They also feed on developing cotton bolls and soybean pods.

Characteristics
The larva start with a white body and black, inverted Y-shaped heads, but the body begins to darken as it grows. Mature larvae have black bumps on the body and vary from tan to green to black. The neck is overall dark with three light horizontal stripes. The eighth abdominal segment has four black spots on their back. Larvae are about 1 to 1.5 inches in length when full grown and a horizontal black stripe runs along each side of the body. While a wide, yellow-gray stripe runs down the back. The pupae is reddish brown. The moths are ash gray with wingspans of about 1.5 inches. The hind wings are grayish-white and the front wings are dark gray with light and dark spots.

Life Cycle
The pupae overwinter in the soil. Spring females lay several mass clusters of 50 to 100 eggs. Then they hatch and feed 2 to 3 weeks and then pupate in the soil with several generations per year.


Fall armyworm Fall armyworm moth

Last Modified: 10/20/2006
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