Note: This recipe has not been verified against a documented source, or disagrees with one. Treat the materials and steps as unconfirmed.
Classic Recipe
Hook Standard dry fly, 12-18
Thread Black 8/0
Materials
Body Peacock herl or black dubbing (small)
Shellback Black deer hair (folded over)
Indicator Bright foam or yarn (tiny, on top)
Legs Black hackle or rubber (sparse)
How to tie it
Mount hook, lay a thread base to the bend.
Tie in a clump of black deer hair at the bend with the tips pointing back over the bend. Bind the butts down along the shank.
Wrap a small body of peacock herl or black dubbing forward to the 80% mark, modest, not fat. The shellback will define the profile.
Pull the deer hair forward over the top of the body as a shellback and tie down at the head. Pull firmly so the hair rounds over the body like a beetle's wing case.
Trim the hair butts, leaving a short stub as a small head.
Tie a tiny dot of bright foam or yarn on top. This is non-negotiable, a black beetle flush in the film is invisible without it.
Optional: 2-3 sparse hackle fibers or rubber legs out each side.