"In the lexicon of the fly fisherman, the words rise and hooked connote the successful and desirable climax; landing a fish is purely anticlimax" Vincent C. Marinaro, 1950
One of the first things that the budding dry fly fisher realizes is that during a mayfly hatch many of the duns (freshly hatched mayflies) go sailing by as the trout feed on something else. That "something else" is the emerger stage of the mayfly - the insect just sub-surface or stuck in the surface film trying to hatch. We really can't see these fellows unless we put our rods down and take out dip nets which we are probably not going to do. We need a pattern that works and this one does.
There is no one "look" to an emerger. That insect can be 1/3 out of the water or 3/4 out of the water or dragging it's nymph suit behind it or not. What we need is something that looks like the average emerger.
Hook - scud or curved light hook size 14 to 20 or smaller
Body - olive or brown 70 denier thread
Thorax - olive, grey or brown hare's mask
Wing - fine deer hair or snowshoe hare. CDC when you get below size 20.
Hackle - Brown or dun colored on the larger sizes and hackle-less on smaller sizes. Hackle should be one size smaller than the hook size or clipped below the hook if you like.
Bob Wyatt's book "What Trout Want" devotes much time to this insect stage and his pattern for it. It was about 20 years ago that Art Lee (I believe) wrote about this stage and his pattern in Flyfisherman Magazine (I believe). All three of us are talking about the same fly.
Change sizes and shades of color to suit the insect that's hatching.
1/15 = Here's the Swift update - For all of those you said that the lower Swift would be cleaned out in January here are the facts: From the gauge downstream is loaded with trout! Fly fishers are catching them! I saw two bait boys in the last two trips and they are catching next to nothing. For those you said that the joint would be cleaned out - go above Rt 9 where the pickings are slim!!