Females begin ovipositing the day after copulation and do so in one batch during a single oviposition event. Shorter and longer oviposition durations are associated with smaller and larger egg masses, which are directly related to female size. Just before beginning to oviposit, females exhibit dispersal behavior. They position themselves on a branch, spread their wings, and extend their abdominal tip around the branch to prepare for oviposition. As they oviposit, they move around the branch aligning the eggs, forming a ring-like structure around the branch. They then cover their eggs with a foamy substance known as spumaline. It has been hypothesized that the spumaline cover protects eggs from predation and parasitism. Offspring pass the winter inside their eggs. Although cold tolerant, they are susceptible to freezing in extreme cold temperatures, with the risk of mortality varying seasonally with changes in temperature and physiology. Not much is known about parental effects on offspring survival during the winter. The only source of energy for overwintering forest tent caterpillar eggs comes from the parental generation. As a result, overwintering performance of the insect should be viewed in the context of parental fitness.