Chrysanthemums and Shasta daisies are often infested in the summer and early fall. Other vegetable crops likely to be injured include bean, beet, celery, potato, pepper, and tomato. On most crops, borers begin feeding on the leaf surface. Later the larvae bore down midribs of leaves into the stalk. Frass and silk near entrance holes are evidence of their presence.
Borers weaken stalks or stems and interfere with the movement of plant nutrients.
Infested stems often lodge. Mature larvae overwinter inside tunnels in stubble, stalks, ears, or other protective plant material. They pupate in spring. During April and May, adult moths emerge. Females do not mate the first day, but most mate within the next 48 to 72 hours.