Shawn recently shared a photo of a mystery bug from the clinch; some thought it may be a crane fly larva; others a caddis, perhaps a cased caddis outta his case.
Anyway I recall Hugh Hartsell's website and a few of his comments once at Troutfest about the Holston having a great many craneflies and did some looking into things last night after fishing a "copy" of Shawn's bug with good results on the Holston.
A guy named WALT YOUNG created a simple fly called "Walt's Worm" that is nothing but a weighted hook with a dubbed body of gray rabbit hair, (my flies were weighted hooks with Orvis Hare's ear ice dub clipped with a brown head of big fly dub also clipped and I used copper wire.
These are too easy to tie so consider trying them out.
Don't know if yesterday's fish thought they ate a "brown headed" crane fly OR a caddis pupa but sometimes the simply tied flies catch lotsa fish.
I used size 14 and 16 hooks 3x long.