Eggs are very small, are seldom seen and are laid at the base of appropriate host plants. Larvae hatch from the eggs and feed mostly at night. They usually hide in debris on the soil surface in the daytime. When full grown, larvae will enter the soil and form the pupal stage. Adult moths emerge from pupae.
Moths mate and lay eggs, thus starting the life cycle over again.
Lush plant growth is preferred by the adults for egg laying. Armyworms in the spring and summer occur in more distinct groups than later in the season. Fall populations of larvae often blend together several generations and may appear to be continually occurring. When feeding, larvae strip foliage and then move to the next available food. High populations appear to march side by side to the new food.