Initially yellowish-brown in color, cocoons become rust brown as they age. In the spring, larvae resume feeding and complete their development beneath a thin layer of the bark surface from pink to shuck fall. Following construction of a cocoon, the larva changes to the pupal stage. In 3-4 weeks the pupa pushes through the cocoon and the thin bark surface, the pupal case splits open, and the moth emerges. Moth flight begins around shuck split or shuck fall and continues for 6-8 weeks.
Moths are active during the day, with mating and egg-laying occurring soon after emergence.
Female moths are attracted to damaged and previously infested trees, and deposit eggs in cracks or under bark scales of wounded sites. Infestation is almost always associated with previously damaged trees. The problem tends to be more severe in older orchards that have a greater incidence of Cytospora canker, winter injury, and pruning and other mechanical wounds. Older wounds appear dark due to the exudation of gum which oxidizes. Larval feeding enlarges the wounded area which eventually results in complete girdling of the trunk or limb.