Thanks for the buzz Christine! I have come across something similar but what that was I don't recall, I think it's a butterfly and not a moth caterpillar.
It's only the adult butterflies which mate, the caterpillar is the 'larva' which will turn into a pupa before it emerges, that's most likely what these were doing, finding a safe place to pupate.
It could be a Buckeye,
http://bugguide.net/node/view/...
Please don't eradicate them.
