How to Manage Pests

Pests in Gardens and Landscapes

Armyworms—Spodoptera spp.

Armyworm larvae feed in groups, which distinguishes them from other vegetable pests such as corn earworms and loopers. Markings on newly hatched armyworms are usually hard to distinguish from those of other caterpillars; older larvae have distinct lengthwise stripes. The surface of the armyworm skin is smooth.

Identification of species | Life cycle

Damage

Armyworms may feed on the crowns of seedlings. On larger plants, armyworm caterpillars skeletonize leaves. In tomatoes, strawberries, and cucurbits they make shallow (occasionally deeper) gouges in fruit.

Solutions

Handpick. Virus diseases, parasites (Hyposoter and Trichogramma), and general predators may be effective on caterpillars. Eggs are protected from parasites by fluff. Bacillus thuringiensis or other insecticides such as spinosad may be used against young caterpillars but are needed only when numbers are high on seedlings. Ignore armyworms in sweet corn, where they do not usually cause major damage.

Armyworm mature larva
Armyworm mature larva

Damaged leaf
Damaged leaf


Statewide IPM Program, Agriculture and Natural Resources, University of California
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