Black Cutworm Life Cycle

Black cutworms feed on the young tender shoots of corn.

According to the University of Illinois Integrated Pest Management Department, black cutworm larvae range in color from light gray to black. When fully grown, this specific species of cutworm averages 1 1/2 inches in length. Nocturnal in nature, the adult moths feature dark gray wings with dagger-shaped markings. Black cutworms prefer healthy turf and will attack corn crops when all other forms of forage are eliminated through herbicide usage in the area. The entire life cycle of the black cutworm requires a minimum of 45 days.

Migration

According to GreenShare, a University of Rhode Island Landscape Horticulture program, most species of cutworms migrate to south during the fall months. Weather fronts during the spring help to propel the adult moths north in the spring when new growth is emerging in lawns and crop fields. According to the University of Illinois Integrated Pest Management, the heaviest moth migration into Illinois occurs during April and May.

Eggs

Female black cutworm moths lay eggs near food sources, such as in fields and overgrown grass areas. Many moths are attracted to areas of winter annual weeds, such as shepherd's purse, chickweed, mustard and peppergrass. Winter wheat also provides adequate egg laying properties. The moths deposit eggs either in a group or individual. The moth places the eggs on the tips of the host grass or plant. According to the Minnesota Department of Agriculture, black cutworm eggs are white, deposited either singly or in small clusters.

Hatching

Larvae hatch within five to 10 days of the egg laying. The Minnesota Department of Agriculture identifies the black cutworm from other species of cutworms by a "greasy black" appearance. The black cutworm larvae features pairs of black dots of unequal size on each segment of the larvae. Feeding on young plants begins within three to six days of hatching.

Larvae

Larvae go through six stages, also referred to as instars. The instars take 28 to 35 days to mature, depending on the temperature of the area. According to the University of Illinois Integrated Pest Management, black cutworms begin cutting plants at the base during their fourth instar. Before this point, the larvae make small holes in the leaves of the plant. The larvae remain in underground burrows during the day, emerging at night to feed. They often move portions of the plant into their burrows in order to feed during the day. The average larva cuts three to four corn plants during the larvae stage.

Pupal

The pupal stage of the black cutworm lasts 12 to 15 days. According to GreenShare, black cutworm pupae are brown, smooth and torpedo-shaped.

Emergence

The black cutworm has the potential to produce as many as six generations per year. Once the pupae hatch into moths, they reproduce and lay eggs on surrounding food sources. There may be many different stages of the life cycle in one location during the growing system. For example, one may find eggs, cutworms, pupa and adults all at the same time. According to the Minnesota Department of Agriculture, the first generation of black cutworms causes the most damage to Minnesota crops.

References

• GreenShare: Cutworms on Turf
• University of Illinois Integrated Pest Management: Black Cutworm
• University of Minnesota Extension: Cutworms in Home Gardens
• Minnesota Department of Agriculture: Black Cutworm

Resources

• UW-Madison Extension and Research: Black Cutworm