Several species of climbing cutworms feed on blueberry foliage, but only the black army cutworm has caused extensive crop losses. In most years, the black army cutworm and other species are present in low numbers, but periodically widespread outbreaks occur to defoliate hundreds of hectares with substantial crop losses. At this time, they feed mostly on terminal buds, eating out the interior after entering through a small hole that they have made in the side of the bud. As the buds grow, the contrast between injured and normal buds increases and infested areas become more conspicuous. The foliage of blueberry and other plants can be completely removed during heavy outbreaks and severely infested areas look as if they had been swept by fire.
Cutworms usually feed at night and rest on the surface debris during the day.
However, during heavy outbreaks and the rapid depletion of food supplies, they develop a marching habit and feed during both day and night, resulting in the complete defoliation of numerous fields. The larvae of the black army cutworm are velvety black during the early instars with a white stripe along the sides. They feed from late April to early June, pupate within the litter layer on the ground, and emerge as adult moths during the latter part of July. The eggs are laid in late July and August and hatch in late September and early October. The larvae feed for a short period and then hibernate until the following spring.