Description: Newly hatched larvae are about a quarter inch long and grow to be about two inches long when full sized. Their color ranges from gray to nearly black. There is a pale rather indistinct narrow stripe along the center of the back. Â
Damage Symptoms: Black cutworms exhibit two types of feeding patterns depending upon the amount of moisture in the soil and size of plants. Where soil moisture is adequate and plants are small, the larvae hide in the soil during the day and move to the soil surface at night where they cut off plants just above the soil surface. This is typical damage for most cutworm species. One larva can cut off an average of five corn plants during its development. In situations of dry soil conditions, the larvae do not move to the surface to feed, but instead, they chew into the plant just below the soil surface. This causes the corn plants to wilt and usually die. Loss of plants in infested fields will vary from 10 to 80 per cent. Seldom is a field completely destroyed, rather severe damage is usually confined to portions of the field.
Scouting: Mid- to late May until corn reaches V5. Look for missing and injured plants, especially in weedy or low-lying, damp areas. Larvae may hide adjacent to cut plants in the soil and under crop residue. Larvae feed at night or during cloudy days but hide in the soil during bright daylight.
Management: Because of the relationship between BCW and weed infestations, early tillage and fall and/or spring weed control will reduce the incidence of cutworm infestations. Weed control can be especially useful if done as a fall management program. Conversely, reduced tillage or no-tillage fields with substantial broadleaf weed infestations may warrant a preventive treatment prior to emergence. Such a treatment might be especially critical if adult cutworm flight is occurring within a region. Preventive control can be achieved by at-planting or pre-emergent use of various insecticides. Corn hybrids with transgenic traits will also control BCW larvae.
Sources:
The Ohio State University
Pennsylvania State University
Iowa State University Extension, Corn Field Guide: A reference for identifying diseases, insect pests and disorders of corn. 2009: 48.
