Intermediate Fly Tying

Part Twenty-seven



Intermediate Fly Tying:

CDC Flies

By Al Campbell


It would be an error to venture into the world of emergers without taking a moment to look at CDC flies. I suspect most fly tyers don't understand the importance of CDC flies or maybe they don't understand where and when to use CDC flies.

First of all, CDC is an acronym for cul de canard, a type of feather found near the preen gland on most birds. However, the CDC we are looking for is found on ducks and geese, especially ducks.

Preen oils collect on these feathers and often saturate them, leading to the myth that it is the oil that makes CDC float. In fact, it's the structure of the feather that makes it float so well. Dyed CDC feathers often don't have any of the preen oil left on the feather, it was stripped during the dying process, but they float as well as the natural feathers.

Preen oils collect on these feathers and often saturate them, leading to the myth that it is the oil that makes CDC float. In fact, it's the structure of the feather that makes it float so well. Dyed CDC feathers often don't have any of the preen oil left on the feather, it was stripped during the dying process, but they float as well as the natural feathers.

What keeps the CDC feather afloat is thousands of tiny barbules extending from each of the many tiny shafts of the feather. These barbules tend to rest in the surface tension of the water better than any other feathers. In addition to that, the many barbules trap air bubbles, creating buoyancy similar to an air mattress. Even if the feather is pulled under the surface of the water, the many tiny bubbles of air will lift it right back to the surface.

Because the feather is designed this way, you should never add a fly floatant to the CDC. Floatants would mat the tiny barbules down and prevent them from trapping air. In other words, if you add floatant, your fly will sink. I believe that's another reason so many people shy away from CDC; they don't understand why it didn't float after they added their favorite floatant, so CDC must be a joke.

No joke here folks, CDC floats like a cork, and it has a definite place in fly tying. I've caught more fish on CDC mayfly emerger patterns than any other mayfly emerger pattern I've used. That's the key; CDC is perfectly suited to emerger patterns. It allows the body of the fly to sink slightly into the surface film, but it keeps the fly at the surface, not allowing it to sink.

Let's look at a couple CDC flies. Once you've seen and mastered the technique, you will be able to tie just about any CDC fly in any pattern book.

List of materials: CDC Mayfly

Mustad 80000BR
  • Hook: Light wire dry fly. Mustad 80000BR or equivalent. Size: 12 to 22.

  • Thread: 6/0 Gudebrod or equivalent, black or color to match body.

  • Tail: Split hackle fibers or you can make a tailing shuck out of a small tuft of antron yarn.

  • Body: Anglers Choice Llama dubbing. (Llama hair is fine and hollow, so it floats very well.) Any quality dry fly dubbing will also work.

  • Wing: Two or three CDC puffs.

  • Tying steps:

  • 1. Start the thread, tie in a tail, and dub a body as shown.

  • 2. Tie down several puffs of CDC with two loose wraps of thread. The CDC should extend back over the body.

  • 3. Grasp the CDC on both sides of the thread and gently slide it forward, keeping it on top, until the wing is extending just to the hook bend.


  • 4. Secure the wing with several more wraps of thread.


  • 5. Trim the CDC that extends over the hook eye.

  • 6. Build a head, whip finish and cement the head.

  • Now, let's try a CDC caddis.

    List of materials: CDC caddis

    Mustad 80000BR
  • Hook: Light wire dry fly. Mustad 80000BR or equivalent. Size: 12 to 22.

  • Thread: 6/0 Gudebrod or equivalent, black or color to match body.

  • Tail: None, or you can make a tailing shuck out of a small tuft of antron yarn.

    Body: Anglers Choice Llama Plus dubbing. (Llama Plus has all the qualities of regular llama hair dubbing plus sparkle.) Any quality dry fly dubbing will also work.

  • Wing: Two or three CDC puffs.

    Tying steps:


  • 1. Start the thread and dub half a body as shown.


  • 2. Tie down several puffs of CDC. The CDC should be adjusted like before to extend back over the body, past the hook bend.

  • 3. Trim the unused portion of the CDC feather.


  • 4.Dub the second half of the body as shown.


  • 5. Tie in a second set of CDC feathers for a wing. Adjust the length of this second wing to stop just short of the hook bend.

  • 6. Trim the CDC that extends over the hook eye.


  • 7. Build a head, whip finish and cement the head.

    Our last fly this week will be a CDC Suspended Midge Pupa.

    List of materials: CDC Suspended Midge Pupa

  • Hook: Light wire curved dry fly or nymph. Tiemco 2302, Mustad 80050BR, Tiemco 200R or equivalent. Size: 16 to 24.

  • Thread: 6/0 to 10/0 Gudebrod or equivalent, black, red, olive or color to match the natural.

  • Tail: Several short strands of antron yarn. (optional)

  • Body: Tying thread.

  • Rib - Fine copper wire.

  • Wing: One or two CDC puffs.

  • Collar: Coarse dubbing, peacock herl or ostrich herl.

    Tying Steps


  • 1. Start the thread and tie in a short tail (optional) as shown.


  • 2. Tie in a copper wire, letting it hang past the hook bend. Build a smooth body of tying thread as shown.


  • 3. Wrap the wire forward, evenly ribbing the body. Tie off the wire and trim it.


  • 4. Tie in several puffs of CDC with two loose wraps of thread. The tips of the CDC puffs should extend over the hook eye.


  • 5. Adjust the length of the wing. It should be 1/2 to 3/4 the length of the body.


  • 6. Tie off the CDC and trim the CDC that extends over the body.


  • 7. Dub a collar over the thread wraps you used to secure the wing. You can use peacock or ostrich herl here if desired.


  • 8. Whip finish, trim thread and cement. Your finished fly will suspend vertically like a natural emerging midge.

    There are many patterns that can be adapted to CDC puffs. Some tyers have added CDC to beadhead nymphs to capitalize on the tiny stream of bubbles that are released when the CDC is pulled under the water by the weight of the bead. Others have used CDC as a source of additional buoyancy under the traditional wing in elk hair caddis and other hair wing patterns.

    There are a few who try to use CDC as a dubbing material. I suppose there might be some advantages to this, but if the tiny barbules are matted down by the tying thread or wax, the CDC is no more buoyant than marabou. I suspect a few companies have tried to capitalize on the popularity of CDC in some circles by exploiting the lack of knowledge many tyers have concerning CDC and what makes it work. After all, if CDC floats, it should make a good body, right? Well, not if you know what property of the CDC makes it so buoyant.

    These are just a few short examples of CDC flies. Do some experimenting on some other patterns, replacing wings or adding to existing wing materials. I've substituted CDC for elk hair in my sparkle caddis patterns with great results. If you have an imagination, I'm sure you can find many more uses for this great fly tying material.

    See ya next week - Remember, I'm always happy to answer your questions, feel free to email me. ~ Al Campbell

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