Laurel Sphinx

cool spotting!

http://www.projectnoah.org/spottings/140.... Maybe this? Mine was the last instar when the tail turns blue.

Her guess. ;)

ForestDragon is correct in his guess. Identification from Bugguide is, "Larva is blue-green or yellow-green with seven diagonal lines that are white edged with black above and usually yellow below. Black stripe on the outer part of head inwardly edged in yellow-green. Spiracles orange, horn blue with tiny black spines. Midabdominal prolegs have yellow band above black crescents at bottom of leg." Here is a close up of the horn and head, http://bugguide.net/node/view/324429

I too believe this is the Fawn sphinx, also called Laurel sphinx, Sphinx kalmiae

This is quite similar to Sphinx kalmiae - Laurel Sphinx:
http://bugguide.net/node/view/3733
Sphinx caterpillars are impressively large!