Depending on diet and temperature, the black cutworm progresses through six or seven larval stages, or instars. However, larvae must reach the fourth instar before they are large enough to cut seedling corn. Although there are several generations of black cutworm in the Midwest each year, only the first generation injures corn. Seedlings cut at or just above the soil surface. Purplish, lodged plants partially cut or notched below ground.
Corn is vulnerable to cutting from emergence through the five-leaf growth stage.
Temperatures must exceed a base threshold, or minimum developmental temperature, in order for an insect to grow. There are several methods, varying in complexity, which compute the accumulation of degree-days. The traps are baited with a pheromone lure that attracts only the male black cutworm moth. The first intensive pheromone trap captures of black cutworm moths mark the arrival of the first significant migratory flight. Intensive captures are indicated when at least eight black cutworm moths are captured over two nights in a sticky wing trap, or at least 17 moths are caught in one night in the larger Texas-style metal cone trap.