The female lays her eggs in masses, usually on branches and trunks of trees. Egg masses can also be found on patio furniture, recreational vehicles and other outdoor items. The egg masses are cream or buff in color and about an inch or so in length. Younger caterpillars are usually feeding in the top of the tree and may go unnoticed on large trees. Older caterpillars may move up and down the tree.
Older caterpillars are very distinct in their appearance.
Feeding by the caterpillars occurs in May and June. The caterpillars mature in late June and early July, then enter a pupal stage. During this time the caterpillars are turning into adult moths. Pupae are dark and do not move. Pupae can be found under bark, in crevices, in sheltered areas and even on the ground.