See if you can spot him before looking at the answer...

You can see he is attached to the branch by his feet and his mouth with hairs on his face at the other end. He is about 1 1/2 inches in length.

This is a Looper Caterpillar which turns into a beautiful brown, white and black moth. Here is more information and another picture.
Most of the Caterpillars in family GEOMETRIDAE only have one or two pair of prolegs. The caterpillars move with curving their bodies into loops. This is why they commonly called Loopers. They are also known as Inch Worms because they apparently measuring off one inch at a time as they move. Some of them are called Twig Caterpillars because in their resting posture, it looks like a twig.
