Location: Upstate New York
May 26, 2016 5:44 am
We found this under a tree. He is about 2 inches long. His underbelly is green with black spots. There are 2 black ‘spikes’ near his rear end. It is almost June here in Albany, NY.
Signature: Abbie Donnelly
We believe based on your image and descriptions that this is one of the Underwing Caterpillars in the genus Catocala, but we are unable to provide you with an exact species. You may browse through BugGuide to see some similar looking Caterpillars. Here is a BugGuide image showing a green underside with black spots.