need help with identification

While out at Keystone State Park bass fishing to-day I spotted what I thought was a Monarch Butterfly caterpiller.Only thing was this critter was HUGE,about4-5" long & thick as my thumb. It was basicaly bright green but it had 2 paralell rows of what looked like mini daisys on its back. Didn't look like the picts of a Monarch on the puter. Any ideas? Was very cool to watch. sam

Google image search cecropia moth caterpillar...is that it?
its probable either: one of the giant silkworm moth caterpillars (Polyphemus, Luna, Cecropia, Imperial, Io)
OR
A large sphinx moth caterpillar. Most, but not all, of the big sphinx caterpillars are hornworms ie. they have a horn at one end of the body. If your caterpillar didn't have a horn then it was most likely one of the giant silkworm moth caterpillars.

Sam,

Did you collect it? Do you plan to raise it? Since you got me interested, I went Googling and found this pretty cool photojournal about a guy who raised a bunch of Lunas from getting the female to lay her eggs, to releasing the fully developed offspring moths.

http://www.facepunch.com/showthread.php?t=822445

It was one of those bugs from Africa that crawl in your ear and eat your brains.

IDK what they are called but some drunk chick today keep telling me about some crazy stuff and finding out how many licks it takes to get to the center of a tootse pop ...I really need to invest in locks.