Cutworms can be a serious pest of crops in South Dakota. Safflower is one of the crops recently affected by cutworms in the western half of the state. The cutworm species responsible for the reported injury was dingy cutworm. Dingy cutworms are considered sporadic pests in South Dakota, and are typically observed during the early part of the growing season. Last year, dingy cutworms were observed in several sunflower fields throughout South Dakota.
Dingy Cutworm Description
Dingy cutworms can be identified by their light brown color, smooth skin, and small spots that are present on each segment of the body. These caterpillars also have a slightly darker line that runs down the center of their back (Figure 1). Dingy cutworms are known to cause extensive defoliation; however, they generally do not cut the plants as other cutworms do.
Figure 1. Dingy cutworm observed in safflower. Credit: C. Graham
Scouting & Management
Dingy cutworms are nocturnal feeders and hide under the soil surface during the day. As a result, scouting often requires a trowel or involves examining areas in the field with increased amounts of debris. Although no threshold exists for dingy cutworms in safflower, management for other crops is recommended when stand reductions reach 25-30%. If management is necessary, foliar insecticides can be used against cutworms. Please refer to the current edition of the South Dakota Pest Management Guide: Alfalfa and Oilseeds for a list of insecticides currently labeled for cutworm management in safflower.