The pink-purple larva is usually found in the stalk or in soil near the base of the plant. Damage may vary from negligible to near total seedling loss. Damage varies from season to season, especially as weed control fluctuates. The adult is a brown, medium-sized moth that emerges in August from its pupa near the soil surface. During September, the female lays 50 to 75 eggs in parallel rows on the leaf sheath of weed grasses in grassy fence rows and borders, or in surrounding weed cultivated fields.
Quack grass is a common host.
The overwintering eggs hatch in May, and the small larvae bore into the stems. By early summer, they have outgrown the stems of their primary hosts and migrate to larger, stalked weeds and cultivated crops. The larvae are distinctly pink-purplish in color with dark bands across the body. There is one generation per year. Because the potato stem borer migrates from weeds to corn, it is possible to control this pest by maintaining weed-free fields, borders, and fence rows.