Moths begin to emerge in late August and quickly increase in numbers, peaking by mid-September. Moth activity decreases by early October. The moth flight coincides with tillage and planting of winter wheat. Moths are attracted to areas with loose soil to deposit their eggs. This may occur from February through March.
Young larvae are small and very difficult to find.
Larvae pass through 6-8 stages before they cease feeding and pupate. As they get bigger they become a grayish-green color. The only other cutworm likely to be present in fields at this time is the army cutworm, which generally is larger because it begins development in the fall. Pale western cutworms feed through the spring and mature in May and early June. They then burrow into the soil and form earthen cells where they pass most of the summer, pupating in early August shortly before they emerge as adults.