This plump bright green worm is one of the stages in the life of a Polyphemus moth. It's a native North American moth that has a wingspan wider than the Luna moth.

I took this photo in the waning days of September. The worm is about 3 inches long and shaped similar to a nice big pecan. In October it will spin a very durable cocoon in which it will spend the winter. The cocoon may hang all winter from a limb, or if the worm drops from the tree, it will burrow into the ground and spin its cocoon there.

The Polyphemus moth is brown in its winged stage. It has hairy wings and body with amazing fake eye patterns on its wings.