The entire development from egg to adult moth requires more than 45 days. This cycle continues until the first frost, and three or four generations are produced each year, although only the first generation causes damage to corn. Back to Top Click on image for larger version Figure 2. Black cutworm eggs Figure 3. Black cutworm pupa Figure 4.
Outbreaks also are more likely to occur in corn planted after soybeans than corn after corn.
The most important of these factors may be late planting and preplant weed infestations. For one, fields that are planted late are likely to develop a preplant weed infestation, and, as mentioned, cutworms lay their eggs in weed-ridden fields. In addition, late planted corn, or corn that is delayed in its development by unfavorable weather, can be attacked by cutworms before the plants emerge from the soil. Small larvae feed on plant leaves, so early cutworm feeding shows up as small irregular holes in the leaves. The larvae feed above ground for about the first quarter of their lives, or until they are approximately half an inch long.