The armyworm gets its name from their habit of marching across fields in a soldierly fashion. These pests feed together in groups on plants, and their typical food sources include grasses, such as oats or barley.
Armyworms can be identified by the stripes of white, orange and dark brown along their abdomens. They are usually about an inch and a half long when mature. Armyworm moths are small, tan moths with wingspans of about an inch and a half. Their wings feature a tiny white spot in the center.
Armyworm moths will lay eggs at night, usually in the folded parts of the leaves of grain plants and grasses that are moist. The eggs are laid in rows that resemble a miniature strand of pearls. The eggs will hatch in 8 to 10 days and the larvae will consume all the food around them until they are fully grown. If food becomes scarce, the armyworms will seek out vegetation in great numbers, travelling like an army on the march. When they are finished feeding, the armyworms will burrow in the soil and pupate. In two weeks, they hatch and mate, beginning the cycle again.
Armyworms will feed at night and also travel during the night on their search for new sources of food. During the day, armyworms will hide under leaves or in the loose soil. Armyworms will feed on and destroy crops en masse, and then move on to the next food source. Since the majority of this activity is done at night, they are often hard to discover before extensive damage has already been done. Early detection is critical, as a group of armyworms can work through the night destroying entire swaths of cash crops, such as grains, sugar beets, alfalfa and beans.