As they grow, they gradually move away from the egg masses. Many small larvae die during this wandering stage but the behavior tends to spread out the infestation. Beet armyworm is quite mobile, one larvae may attack several plants in a row. Older larvae may feed on fruit as well as leaves. The life cycle takes about a month to complete in warm weather.
Beet armyworm feeding on young tender growth can be very damaging to small transplants.
Often a fine webbing is produced by smaller larvae near these feeding sites. Older plants can become rapidly defoliated . Vegetable growers should pay particular attention to fall plantings of beans, tomatoes, crucifers, and other truck crops. Timing of insecticide applications is very important. So treatment must be targeted against young larvae.