Note: Contested against a published dressing: This is unambiguously the right page — hook (TMC 2488 #18), thread (UTC 70 olive), Mirage opal flashback and Superfine thorax all match exactly. But TWO MATERIALS ARE IN SWAPPED ROLES in our record. Source: Fly Fish Food (Cheech) — "Mil Spec Mayfly Nymph", Nymph Tutorials — https://www.flyfishfood.com/blogs/nymph-tutorials/mil-spec-mayfly-nymph
Reference Recipe
Hook Curved-shank nymph hook (TMC 2488), 18
Thread Olive UTC 70
Materials
Brahma hen fibers (tail) Natural mottled grouse feather (small bunch)
Brown marker (rib) Brown permanent marker (as needed)
Mirage/opal tinsel (flashback) Opal mirage tinsel medium (1 strand)
Superfine dubbing (thorax) Brown olive ice dub (tiny pinch)
How to tie it
Flatten the thread and lay a base to the midpoint; angle the hook down in the vise and tie in a short bunch of Brahma hen fibers at the bend for a tail no longer than the body.
Spin the bobbin counter-clockwise to keep the thread flat and build a slight tapered thread body, wrapping down and back up and finally to the rear.
Color a section of the flat thread with the brown marker, then wrap it forward in barber-pole spacing to form a subtle rib to about the thorax.
Tie in a strand of opal mirage tinsel for the flashback, then tie in a small bunch (10-12 fibers) of sparkle emerger yarn at the hook point for the wing case.
Dub the barest pinch of brown-olive superfine onto the thread and wrap a thorax, leaving room up front for a pronounced head.
Pull the emerger yarn forward over the thorax, then the flash over the top of it, tie both down behind the eye, and whip finish.