Pale Western Cutworm, Agrotis orthogonia
Pale western cutworm is a subterranean cutworm, feeding on stems at the crown. They can be a significant pest in wheat and corn but will feed on a vast array of crops and weeds. Feeding results in severed stems, and entire fields may be lost in a matter of days.
Order: Lepidoptera
Family: Noctuidae
Description and Lifecycle
Mature larvae are 1.5 inches long, smooth-bodied, and a white or grayish color. Adult moths have a wingspan of 1.5 inches, are light grey, and have several distinct cross lines on the tips of the forewings. Adult moths emerge from the soil in late summer and fall, generally August. Most egg laying occurs in September in loose soil. Eggs usually hatch in late winter. Larvae prefer loose, sandy, or dusty soil and are found most easily in the driest parts of the field, such as hilltops. After feeding is complete, larvae move to pupal chambers constructed several inches below the soil surface.

John Capinera, University of Florida, Bugwood.org.
Pale western cutworm adult.

Phil Sloderbeck, Kansas State University, Bugwood.org
Pale western cutworm.

Frank Peairs, Colorado State University, Bugwood.org
Pale western cutworm larva.
Quick Facts
- Pale western cutworm is a subterranean cutworm, feeding on stems at the crown. Feeding results in severed stems, and entire fields may be lost in a matter of days.
- Mature larvae are 1.5 inches long, smooth-bodied, and a white or grayish color.
- Larvae prefer loose, sandy, or dusty soil and are found most easily in the driest parts of the field, such as hilltops.
- Outbreaks are associated with dry conditions during the previous spring
Injury
- Pale western cutworm is a subterranean cutworm, feeding on stems at the crown. Feeding results in severed stems, and entire fields may be lost in a matter of days
- Pale western cutworm are mostly nocturnal feeders
- Leaf feeding, wilted leaves and dead tillers are good signs of cutworm feeding
- Small grains such as wheat, corn and other crops are attacked by pale western cutworm. They have been known to occasionally host on weeds as well.
- Outbreaks are associated with dry conditions in the previous spring
Management
- Pale western cutworms tend to concentrate in favorable (i.e., dry and sandy) parts of the field, so it is important to sample the entire field before making any management decisions.
- Start scouting early in the season to avoid severe damage to areas where the larvae concentrate.
- Adult monitoring can be achieved by using pheromone traps from mid-August through the end of September to aid in decision making in the spring.
- In the spring, scout for larvae by digging from a foot row (3 inches deep) between rows of the crop and sifting for larvae.
- Action guidelines suggest treatments for pale western cutworm when one larvae per square foot is found if the crop has good yield potential, or two larvae if the crop has low yield potential.
- Because of the sporadic nature of pale western cutworm outbreaks, management is limited to insecticides.
CSU Extension Fact Sheet
Download or view the CSU Extension’s PDF fact sheet for your reference.