Armyworms typically become a pest of wheat just before, and during heading.
Damaging outbreaks are usually associated with cool, damp springs. Armyworms are often more numerous in low-lying areas, areas where wheat has lodged, or in fields that have dense plant stands. Caterpillars feed first on the leaves, then on the awns, and may finally feed on immature kernels that have not reached soft dough stage. They hide during the day, preferring to feed at night or on overcast days. Armyworms have been known to eat the green stem tissue just below the base of the grain head and clip it off, however head clipping in wheat is rare.