Experts from the University of Nebraska-Lincoln’s Institute of Agriculture and Natural Resources recently shed light on the need for army cutworm scouting, particularly in Western Nebraska alfalfa and wheat. They note that the army cutworm, of all cutworm species, is one of the most damaging in the region.
Army cutworms typically survive in Nebraska over the winter as larvae within the soil, making them one of the first caterpillars to be seen in the spring. Last year, the cutworms laid their eggs on bare soil and after a series of rainfall, these eggs hatched. The caterpillars then fed and continued to grow until the temperatures dipped. They burrowed underground to wait out the winter, and are just now starting to reemerge and feed.
The army cutworm larvae are greenish-brown to greenish-grey in color, and anywhere from a half-inch to two inches in length. In 2019, moderate populations of the adult army cutworm moth (or “miller moth”) were found in sheltered areas of western Nebraska.
Feeding damage from army cutworm larvae may vary in appearance. The larvae often graze leaf tips, but they also chew on the sides of wheat seedlings. Infested fields often draw large flocks of birds, particularly in the morning hours, as they tend to feed on army cutworm larvae.
A treatment threshold of four or more cutworm larvae per square foot of winter wheat or alfalfa can be used to scout for the pests. For stressed, thin strands of wheat or newly established alfalfa stands, a threshold of two or more larvae per square foot may be used. If army cutworm counts are above the threshold, an insecticide should be considered.