Army Worms

Army worms favorite foods are turfgrasses and grains that are planted in the fall. Cool wet weather helps to increase their number. This is also the time when most turfgrasses are at their peak.

Their eggs are deposited on or near plant foods. The egg masses may contain several hundred new worms. Each female may deposit several of these clusters. The eggs are green at first but later change to brown. They are often covered with moth scales.

Temperatures influence the period of time until the eggs will hatch. During the cooler fall months, eggs will hatch on an average of 11 days.

In the early stages the larvae tend to congregate but as they age they scatter in search of food. The larvae feeds mostly at night or on cloudy days. If the plant is young and succulent, the army worm will eat it to the ground. You may recognize them by the following ways:

A white "Y" on the head.

3 yellow stripes down the back.

A dark band on either side of the stripe.

Prominent tubercles on the back.


The most common damage on most turf is defoliation. Early damage to turfgrasses shows up as a loss of chlorophyll. A lawn may be defoliated in only 3 days. In this short time the larva reach maturity. Unless the plant damage is severe, most turf recovers in a 1 to 2 week period.

When army worms are full grown they are about 1 1/3 inches in length. They may be tan, green or black. The larval stage varies from 12 days to 40 days, depending upon the season. A frost usually kills the larvae.

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