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Adventures in Fly Tying... December 2007

The CDC "One Feather" Emerger
Fly and Text by Joe Cornwall
Video Production by Jim Stuard


I tie a lot of flies and I enjoy it.  I like the "sculpture in reverse" activity of building a fly.  And most importantly I enjoy catching fish on the flies I tie.  There's nothing quite so satisfying as fooling a fish on a pattern you created, tied to a leader you built, in response to a challenge you found at a local fishing spot.  That said, I don't enjoy spending hours at the fly tying bench tying just a few flies that are complicated, expensive and no more productive than the impressionistic quick ties I nearly always use.  If catching a difficult fish on your own fly is one of the most satisfying angling experiences, losing a fly you've spent half an hour to construct, on the very first cast, is one of the most frustrating.  I like flies that I can leave in trees or stuck in logs without hesitation.  I'd always rather break off than wade through a spot that might hold a good fish.  Flies should be expendable.

I like quick and easy ties.  Many call them "guide" flies.  This is one of the best and the easiest.  It's also amazingly effective. The CDC "One Feather" Emerger can be tied by even the greenest beginner in just a few minutes.  If its not perfect, it's even better!  The CDC One Feather will catch about any fish that eats bugs,  And, when tied in a few different colors, it can be a good match for anything from a caddis to a mayfly, or from a large Hexagenia to a tiny Blue Winged Olive.  The CDC One Feather fishes well in sizes 10 to 20. It floats on, or just under, the surface.  And if you hang one off the back of a weighted nymph like a wooly bugger, the CDC One Feather makes for a sterling soft hackle.  The material provides lots of inherent motion, which fish perceive as a living thing.  And with just one readily-available feather, this is about as inexpensive a fly as you'll ever tie. 

What is CDC?  CDC stands for cul-de-canard, a feather that translates as "bottom of the duck."  It really doesn't come from the bottom of the duck, but from an area around the preen gland just above the duck's tail feathers.  These feathers surround the preen gland and hold the oils the duck uses to waterproof its feathers.  They are very fluffy and trap a lot of air, making for a fly that floats all by itself.  When forced under the surface the CDC captures many sparkling bubbles of air that shine and attract the attention of game fish. And the hundreds of tiny plumes always move, imitating the legs and antenna of an emerging insect. 

Try this one on the picky rainbows of the Brookville tailwaters or the fussy brown trout of the Mad.  Fish a size 18 behind a weighted nymph until about April. Then switch to a size 14 fished in the surface film as the Hendricksons and Quill Gordons start to emerge as the weather warms.  Fish a size 10 for spooky bluegill or post-spawn smallmouth.  And carry a size 18 or 20 for those late summer midge emergences.  Carry them in Ohio and in Montana.  Carry them with your nymphs or with your dry flies.  This is a versatile and effective pattern!  Carry a few and see for yourself!


Hook: Mustad 94842 dry fly hook or similar, size 10 to 20
Thread: 8/0, 70 denier in a color to match the body feather - either gray, olive, yellow or brown

Tail:  Tip of the CDC feather
Body: Twisted "rope" of CDC

Wing: Loop of CDC with the fibers trimmed to a point equal to the hook's bend

Head: Thread head finished with two whip finishes or a series of half-hitches

Windows Media Video  QuickTime Video 



"Cul de Canard" is a French language term that was created more than half a century ago by tier Henry Bresson for one of his patterns. The literal translation into English is "duck's butt" or "duck's ass" feathers. The unique, fluffy CDC feather isn't located where its English name iimplies, though.  It's located on the back of the bird, a short distance up from the tail feathers. CDC is available in many colors from any well-stocked fly tying shop.  If you hunt ducks, or have a friend who does, they are easy to pluck from the bird.  Goose also have CDC feathers of a larger size - a great choice for imitating large flies like Hexagenia, gray or green drakes.
Stroke the fibers towards the tip of the feather so they all align.  Lay down a foundation of tying thread and tie the CDC feather to the hook shank right above the hook barb.  The tips of the feather should extend back about the width of the hook's gape, forming an short, sparse tail. If the tail is too full, trim a few fibers out.
Advance the thread back to the hook eye.  Hold the CDC feather straight up and twist it into a rope.  This becomes the body of the fly.  Don't twist too tightly, you don't want to break the CDC stem.
Wrap a slim body up to the eye of the hook.  The body will taper slightly. This is a natural and aesthetically very pleasing shape that is a result of ever more fibers being trapped into the rope or "yarn" of the twisted CDC feather.  If you want to make a more durable fly you can tie in a length of heavy tying thread, such as a piece of 3/0 black, and counter-rib the CDC feather.  The teeth of a trout, or the tips of your forceps, will likely cut both the thread and CDC eventually, so I always think of this as a one or two fish fly.  They are so easy to make that I seldom care if I go through six or seven in a day's fishing.  I'm happy to tie six more flies if it means I catch 12 more fish!
Tie off the CDC on the side of the hook closest to you - this is the left side of the hook looking towards the tail from the eye.  Now take the CDC feather and form a short loop with the tag end coming down on the right side of the hook (opposite you if your right handed).  Tie off the feather.  Form a neat thread head and use a series of half-hitches or two whip finishes.  Putting head cement on this fly isn't a good idea as the cement may get wicked into the feather, destroying its natural floating ability and incredibly delicate motion.
Pull the long barbs of the CDC plume up and away from the fly. Trim them with a blunt cut to they stop just short of the end of the tail, just above the back of the bend of the hook.  If you are tying this fly in a size 12 or 10 you may need to use a second CDC feather to form this wing loop.  Some CDC is long enough to tie this fly all the way to a size 10, but many of the feathers will yield size 18, 16 and 14 with much better results.
The finished fly is airy, light and translucent.  It is impressionistic of many aquatic insects.  This CDC fly fishes on the surface (don't use a paste or liquid floatant - just dry the fly on an amadou patch from time to time).  It also fishes well  just under the surface film as an emerging nymph just trying to break through the meniscus.  This is also a great fly to fish like you would a soft hackle - try hanging this off the bend of a heavy nymph and dead drifting it through deep slow pools for lethargic winter trout!

Till next time, tight lines and clear flows…

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