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CDC Biot Caddis Emerger
By B. Moose Peterson

A number of local fliers had mentioned they were having some great results with CDC Caddis Emergers. No one particular pattern was thought any better than the rest, so I went looking for possible pattern ideas that I could either tie or give stimulus to my own variations. I came across this beaut by Harry Mason, which really imitates our late winter hatch really well. With only a couple of slight changes, I tied some up and went and caught some nice Browns. While it might look like a complicated fly, it's really easy to crank them out. Fished only in calm waters, my version barely stays on the surface. This fly illustrated here was tied on a size #14.

Materials List:

    Hook: TMC 5212 #14-16 (2312 optional).

    Thread: Brown 8/0.

    Tail: Yellow/Amber Antron (short).

    Body: Olive Turkey Biot.

    Rear Thorax: Olive Antron.

    Underwing: Blue Dun Antron.

    Overwing: Olive #4 CDC tied flat.

    Legs: Overwing tied down and back.

    Antennae: Two Lemon Wood Duck fibers.

    Front Thorax: Peacock Herl, single strand.

Instructions - CDC Biot Caddis Emerger:

1. Start by crimping down the barb and tying the thread on a third of the way down the hook shank.

2. Cut a section of Yellow Antron off the spool and then split the antron fibers so you only use half of them in creating the tail. I tie the tail on with a couple of wraps and then cut it short. The tail is no longer than the distance to the curve of the hook. "Fluff" the tail as best as you can.

3. Tying in an olive turkey biot is done with just a couple wraps. Once done, advance the thread back up the shank to just past the halfway point on the shank. Wrap the biot up the shank. Keep tension on the biot as you wrap and use some care to space it out over the previous wrap to create the ribbing effect.

4. Wrap the biot past the spot where you've stopped the thread. Very carefully, make your first wrap of thread around the biot to secure it. If you pull too tightly at this point, you will more than likely cut the biot with the thread and start an unwinding panic. After you have the first securing wrap, wrap a couple of more wraps that are now tight. Trim biot.

5. Over the tie off point of the biot, tie in the olive antron that forms the rear thorax. It only requires a couple of wraps of antron to make the thorax.

6. Tie in the blue dun antron underwing over the tie off point for the thorax. Use a couple of wraps and snug it down to pinch the antron against the shank. With this accomplished, trim off the front antron right to the wraps. The rear antron, pull backwards. With the antron tight, cut it right above the junction of the tail and biot. When you let go of the antron, it should snap back and pop up as illustrated.

7. Using #4 olive CDC, tie in two feathers as overwing. You want to tie these in flat. You want the length of the overwing to be just slightly longer than the underwing.

8. This can be the only tricky stage of tying this fly. You want to take the butt ends of the CDC, split them with the hook shank and pull them down and back. You then tie them off to hold this position. This creates the legs. You trim the tied down CDC just above the barb of the hook.

9. Tie in two lemon Wood Duck fibers. You want to tie them in using their natural curvature to have them curve over the back of the fly. The antron and CDC will keep them up but the curve works for you when the fly is wet.

10. Wrap in peacock herl to create front thorax. I use just one strand. The tapered look of the thorax comes from starting the wrap over the CDC/Wood Duck fiber junction and then winding forward towards the eye. Tie off and create the head.

11. Finished fly.

Photographic note:

Photos captured by Nikon D1H, 60f2.8AF Micro with SB-29s flash on Lexar digital film. ~ Moose

About Moose:

Moose is a professional wildlife photographer, and obviously a fine fly tyer, who lives in Mammoth Lakes, CA. He has an extensive website to furnish wildlife photographers with information to make the most of their photographic pursuits. You will find it at:

For more great flies, check out: Beginning Fly Tying, Intermediate Fly Tying and Advanced Fly Tying.

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