Yikes!
I'm not an entomologist, and could be way off base - but this is the first year in recent memory that I've not had forest tent caterpillars totally defoliate most of the young bur and bur-hybrid oaks in yard and along my driveway - they'll do it virtually overnight, and seem to feed at night, and disappear into the grass during the daylight hours - only once or twice have I managed to catch one of 'em "in the act".
But, at my place, they usually hit shortly after initial leaf-out; the trees releaf and have the rest of the season to recoup.

Thanks for the help! I was hoping to get more responses...this has to be THE ideal "help" post...hehe

I did some sleuthing and have narrowed it down to Anisota peigleri (Yellowstriped Oakworm). What do you all think?

That's as good a guess as any. I had a good look at your photo the other day and my first thought was walnut caterpillar or yellownecked caterpillar, but those two don't match the ones you have. Chances are the tree will releaf before the end of the season. A healthy dose of Bt would have taken care of them if you had noticed them feeding, but like lucky_p says, they do work fast.

Make a note in your calendar for next year.Start looking for them in mid-July, or whenever your Extension service reports sightings. Your service would probably be Clemson.

Not a goner. Should be fine come spring. I have one small tree they did the same thing to this year. No big deal.

Given your location, it's somewhat more likely to be the very similar orangestriped oakworm (Anisota senatoria), although I wouldn't rule out either one. I agree with the others - there's a good chance it will releaf this year, and even if not, it's not necessarily a goner.

This post was edited by saccharum on Thu, Aug 15, 13 at 16:02

Great news! Of course I pull into my driveway today and notice my willow oak is under a similar siege. I wonder if the HOA will come and take a look at it :(