Fall armyworm (Spodoptera frugiperda) does not overwinter in North Carolina. Moths migrate into the state each year and low caterpillar numbers can often be found by late May in the northern Coastal Plain. Only late planted corn, after early to mid May, may become seriously infested. Thus, the major tactic for preventing loss to this insect is to avoid both late planting and very late maturing hybrids (e.g. 126 RDM). The recent trend to plant tropical corn in mid-season for silage invites serious infestation by fall armyworm (and other late season caterpillar pests). See scouting guidelines for mid-season insects.
If severe infestation occurs (50%+ of plants with caterpillars) grain yields may be reduced by the leaf feeding; 100% infestation will result in about 18% grain yield reduction in a 140 bu/A corn crop. If caterpillars are present as tasseling begins, caterpillars move from the whorls and eat into the side or tip of the ear. Several caterpillars may infest ears. This insect may seriously affect popcorn, white corn, and seed corn if the crop matures late.
Some Bt proteins effectively control this insect. In non-Bt corn, control of larger size fall armyworms with insecticides is very difficult. All late planted corn may be scouted on a weekly interval for small fall armyworms until plants are near the tassel stage. Small caterpillars are more easily controlled and it is important to treat an economic infestation before it spreads and becomes entrenched in the whorl. See scouting guidelines for whorl feeding insects.