Larvae form an overwintering cell near the base of the stalk in late summer. When larvae total 25 to 30 or more per stalk, stalks are weakened and are susceptible to breakage during high winds or drought conditions. Most management is directed at the adult stage. When populations are large, systemic insecticides applied at planting are effective at controlling larvae in the stalk. Scouting for the adults is recommended from mid June to mid July.
Treatment is warranted when there is one adult found per three plants.
The larvae will feed on the florets until the third instar. As seeds form, the larvae tunnel into the top of the seed. A single larva may destroy 5 to 7 seeds. Small areas of silken webbing in mature heads indicate larval feeding. Scouting should occur from mid July to mid August when the adults are most active.