As Bryon said in the report, the Southern Appalachains probably have more different species of beetles than mankind will ever discover. I had a fantastic day just above Elkmont middle of day on the 4th of July last year throwing Beetles along the shaded edges, under clusters of overhanging branches etc. I believe I caught between 12-18 nice fish in a few hours and not very far upstream.
Also try fishing the entire water column, when fishing as a dry doesn't work. I rarely use hackle if any, on my beetles prefering to fish them in the film or adding a microshot and fishing them wet. I've had times in the park when I couldn't get any action on a beetle when fished as a dry but did well when the beetle was sunk.
My terrestrial box is composed of beetles, a green san juan worm and winged ants but the beetles see the most action.
Randy Sale