I spotted these moths on the side of a dirt road that was passing through a field of sunflowers in bloom, and a friend did a preliminary identification of these as tulip-tree silkmoths (Callosamia angulifera). It appears that the female has just emerged from her cocoon (seen above the two moths). Long Creek, South Carolina is just a few miles from the Chattooga River, which forms the border with Georgia at that point. This is my first submission to BugGuide --- fascinating website.