Webworms
Garden Webworm, Loxostege similalis (Guen.)
Alfalfa Webworm, Loxostege commixtalis (Wlk.)
Beet Webworm, Loxostege sticticalis (L.)

PLANTS ATTACKED: Webworms are general feeders on alfalfa, clovers, cowpeas, peas and similar crops. They also feed on several species of weeds, especially pigweed.

DESCRIPTION: Adult. Garden webworm-- This species probably is the most common webworm that attacks forage crops, and it is the only one described in this publication. The adult is buff with shadings and irregular marking of light and dark gray. It has a wing-spread of about 3/4 inch. The moth is active primarily at night and is strongly attracted to lights. However, frequently it is noticeable in the field during the clay, since when disturbed, it makes short flights of several yards and then alights in a hidden part of the foliage.

Larva. The larva is about 1 inch long, yellowish or greenish to almost black with a light stripe down the middle of the back. The presence of three dark spots forming a triangle on the side of each segment is a distinguishing characteristic of the larva.

LIFE HISTORY: The webworm passes the winter as a pupa or larva within a silk-lined cell in the soil or under plants fed upon by the fall generation. The moth emerges in the spring and lays eggs in masses of two to fifty, primarily on the leaves of the host plant. The egg hatches in 3 to 5 days and the larva begins feeding on the underside of the leaves. The worm matures in about 1 month and goes into the ground for pupation. Three to six generations occur annually.

DAMAGE: Cultivated crops frequently are attacked by these worms migrating from weeds which they have devoured. The larvae feed primarily on the underside of leaves, more or less skeletonizing them. They spin webs and draw other leaves within their webbing as additional food is needed. Flimsy webs near the plant terminals are noticeable in alfalfa infested with these insect.