Comparadun
The Comparadun deletes the hackle - a flared deer-hair wing and bare body sit flush in the film, the profile picky flat-water trout actually see in a real dun.
On slow, glassy water, educated trout inspect a dry fly's underside - and traditional hackle looks like a cage of legs no real mayfly has. The Comparadun (Caucci & Nastasi's 1970s design) answers with radical simplicity: a 180° fan of deer hair for a wing, a naked body in the film, and nothing else. It's what the fish sees when it sees a real dun.
What it imitates
A specific adult mayfly, honestly rendered: body in the film, wing up, no impossible hackle-legs - tie it in the hatch's color and size.
When & where it wins
Flat pools, spring creeks, tailwater sipping fish - everywhere the classic hackled dries draw refusals. The Sulphur and BWO comparaduns are tailwater currency.
How to fish it
Dead-drift on light tippet with reach casts and slack - the flush ride is fragile to drag. One good presentation beats ten mediocre.
Sizes & variants
14-20 in the local hatch colors; the Sparkle Dun (trailing Z-lon shuck) adds the emerger vulnerability picky fish target.
Tying notes
Three materials - hair, tail fibers, dubbing - but the flared wing's proportions are everything; a fine-tipped deer patch matters.
Common mistakes
Fishing it in riffles (it drowns - that's Humpy country), heavy tippet ruining the flush drift, and skipping floatant on a fly with no hackle to shed water.