There are a great many species of cutworms. While they all feed on plants by chewing, they vary as to damage done and host plants preferred. Generally they destroy more of the plant than they eat. Their numbers vary greatly from year to year and, when numerous, may destroy as much as 75% of a crop. Cutworms injure plants in four major ways:
Solitary surface cutworms cut off young plants at or slightly above or below the soil line, sometimes dropping the severed plants into their burrows. Because most of the plant is not eaten, these cutworms do great damage, attacking and felling new plants nightly. The black, bronzed, clay-backed and dingy cutworms are in this group.
Climbing species, usually the variegated and spotted cutworms, climb the stem of trees, shrubs, vines, and crops and eat the leaves, buds and fruit.
Subterranean species, particularly the pale western and glassy cutworms, remain in the soil and feed upon roots and underground parts.