This is the pattern I made for my Yellow Hornberg.
Hook: TMC 2302 "Hump shanked, Down eye Nymph" Size 10
Thread: White 8/0 Unithread
Tail: Yellow dyed Buck Tail
Body: Yellow Rayon - "Domuilles Heavy Flat Floss"
Wings: Mallard Wing (one cut, not from each of a pair)
Hackle: Dyed Yellow
After Tying on, Secure a thread of Copper wire. Wrap wire down just before bend of hook.
Tie in one long strand of Rayon Floss. Wrap to cover over wire and back to head. Secure at head.
Tie thread over floss 1/3 of the way down the shank. Tie in tail (only 3 to 5 strands of Yellow Bucktail). Cut any extra hanging beyond 1 CM from the hook.
Tie wing as a tent over the tail to end just before the end of the hook.
Tie in hackle (sweet spot - in the webbing). Tie secure hackle just before the eye.
Cut down hackle to be no more than 2 CM in lenght (leaving behind only the part of the feather closest to the barb.)
As you can tell, this is a fly used as a wet only. Sinks at a rate of about 1 foot per every five seconds. Nice action when pulled to retreive. (caught a fish on the first pull, remember???)