This is the largest North American moth and is only found east of the Rockies. The adult moth has a wingspan of 4 to 5 inches with distinctive wing markings.

The green caterpillar is over 4 inches long with numerous tubercles of various colors. It feeds on a variety of leaves, including willow, maple and ash. When the caterpillar is ready to pupate, it spins a cocoon that is attached along its length to a branch or stem. The cocoon is brown or gray, depending on age.

The moth shown here was just emerging in late May, its wings were not yet hardened and it moved very slowly. In 30 minutes it climbed from a button bush, up rush stems (Juncus effusus) and to the boardwalk a few feet away.