Cutworms

The variegated cutworm and the black cutworm can both cause damage to beans. Cutworm caterpillar larvae normally hide under debris on the soil surface during the day, and are active, voracious feeders at night. Fully-grown larvae range from 1 to 1.75 inches in length. If disturbed, they will often roll into a tightly coiled "C" shape.

Adult cutworm moths have dark gray or brown front wings with irregular spots or bands and lighter hind wings, with a wing span of 1.25 to 2 inches. Eggs are somewhat flattened on top, white to dull or off-white, and ribbed. They are generally deposited in masses of multiple irregular rows. Eggs may be deposited on crop foliage, but are also frequently found on weeds, close to the ground.

Cutworms cause the most damage during spring and early summer months. They can cut young plants off at the base or near the ground level. Some may also climb up plants to feed on the foliage, leaving ragged holes in leaves.

Eliminate winter weeds within and adjacent to the field well before planting to reduce cutworm numbers in fields.

Use cultural controls for an organically certified crop.

Start inspecting plants for cutworm damage when the crop emerges. Dig into the soil surface to determine the extent of the infestation and the size of the cutworms involved. If the cutworms are reducing the plant stand, apply an insecticide during the seedling stage. Frequently, the damage is most serious at the edges of a field but stand loss may occur in a spotty pattern throughout the field.