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Slate Pool CDC Mayfly Dun

by @dekasso

Slate Pool CDC Mayfly Dun — a fly pattern by Dekasso
More by @dekasso

CDC Dun · Dry fly

A pale dun drying its wings on still water

A slim CDC mayfly dun in pale olive and white, size 16, for trout rising to duns on slow, clear water.

A small mayfly dun with two long barred tails, a slim ribbed body and a loose upright wing. It is wrapped in pale olive thread ribbed with dark olive, under a ragged white CDC wing.

Pattern
CDC Dun
Imitates
Pale olive mayfly duns, typically late spring into summer, often from midday into evening
Hook
size 16
Tippet
5Xrule of three
  • Two split Coq de Leon tail fibers
  • Slim pale olive thread body
  • Dark olive rib marks the segments
  • Loose white CDC wing
  • Size 16 dry-fly hook

On the water

A dry fly riding the surface of a trout river

Two fine barred tails flare wide behind a pale olive body. Thin dark olive ribs mark the segments. A white tuft of CDC stands up over the thorax, loose and a little untidy, like wings still drying.

Fish it on slow glides and flat tailouts where trout sip duns off the top. Cast above the rise and let it drift dead with no drag. A slack line and a gentle mend keep it riding as a real dun would.

CDC wants room to breathe. Keep the wing fibers loose, tease them out after tying, and dress them with a dry powder so the barbules trap air and hold the fly in the film.

A coiled leader, tippet spools and an open fly box on slate

Rigging

Tippet
5Xhook size divided by three
Leader
Nine feet, tapered — longer and finer in flat water
  • Use 5X to 6X tippet and a long, soft leader so the dun lands lightly.
  • Dress the CDC with a dry powder only; gels mat the fibers and sink the wing.
  • After a fish, squeeze the fly dry in a cloth and fluff the wing before casting.

Where and when

Hatch
Pale olive mayfly duns, typically late spring into summer, often from midday into evening
Target
Trout
Water type
Slow glides, flats and spring creeks with clear, smooth water
Also fishes
Also works as a dun on lake margins during a calm evening hatch, and on slow pockets of freestone rivers.

Make it yourself

Intermediate6 materials · 12 steps

Pattern
CDC Dun
Style
Dry fly
Hook
Standard dry-fly hooksize 16
Thread
Pale olive 8/0
Fly-tying materials laid out on a dark bench

Materials in the order they go on the hook

  1. TailBarred Coq de Leon fibers, two, split
  2. RibDark olive thread
  3. BodyPale olive thread
  4. WingWhite CDC
  5. ThoraxOlive superfine dubbing
  6. HeadPale olive thread

Details

Imitates
Mayfly
Colors
Pale olive, White, Dark olive, Grey barred
A fly-tying vise holding a bare hook on a wooden bench

How to tie it

The steps, from first wrap to whip finish (12)
  1. Mount the hook and start the pale olive thread behind the eye, laying a smooth base back to the bend.
  2. Build a tiny thread bump at the bend to act as a tail splitter.
  3. Tie in two Coq de Leon fibers, one on each side of the bump, about one and a half shank lengths long, so they splay apart.
  4. Tie in the dark olive rib thread at the bend and leave it hanging.
  5. Wrap a slim, gently tapered thread body forward to the 70 percent point of the shank.
  6. Spiral the rib forward in five or six even turns and tie it off.
  7. Stack two white CDC feathers and tie them in on top at the 70 percent point, tips forward, so the wing is about one shank length tall.
  8. Pull the wing upright and place a few thread wraps in front of it to prop it in place.
  9. Dub a small olive thorax around the base of the wing, a little fatter than the body.
  10. Form a small, neat head behind the eye.
  11. Whip finish and trim the thread.
  12. Tease the CDC with a dubbing brush to open the fibers into a loose, ragged wing.
Proportions (4)
  • Tail: two fibers about one and a half shank lengths, split wide at roughly 45 degrees.
  • Body: thread from the bend to 70 percent of the shank, slim and tapered.
  • Wing: CDC about one shank length tall, set at the 70 percent point.
  • Thorax: short and slightly fuller than the body, filling the space between wing and head.
Tips (4)
  • Pick Coq de Leon fibers with clear dark bars; the barring reads well on a split tail.
  • Flatten the thread by spinning it counterclockwise for a smooth body with crisp rib lines.
  • Keep the thread bump at the bend small; a big one makes the tails stick out sideways.
  • Leave the CDC loose rather than trimming it square; the open fibers hold the fly up.
Common mistakes (4)
  • A lumpy body from too many wraps. Use few, flat turns and build the taper slowly.
  • Tails tied too short or bunched together. Tie each fiber in alone against the thread bump.
  • Crushing the CDC with tight wraps. Use firm but few turns at the wing base.
  • Crowding the eye. Leave room for the thorax and a small head before tying in the wing.
A dozen-fly materials kit laid out on slate with its recipe card.
The kit

Every kit size

Materials only

Size 16 · Materials only · 12 flies

$34.60

$2.88 a fly

Includes Standard dry-fly hook · and 7 more

Every item in this kit · 8 items

Hooks & beads

  • Standard dry-fly hook$6.501 × 25 · size 16

Thread & wire

  • Pale olive 8/0 thread$2.951 spool
  • Dark olive thread$3.251 spool

Materials

  • Other material: Barred Coq de Leon fibers, two, split$4.501 pack · From the recipe row "Tail"
  • White CDC$6.951 pack
  • Olive superfine dubbing$4.501 dispenser

Finishing

  • Head cement$5.951 bottle

Guide

  • Printed recipe and tying stepsIncluded1

Size 16 · Materials only · 48 flies

$66.41

$1.38 a fly

Bought separately $69.90 · you save $3.49

Includes Standard dry-fly hook · and 7 more

Every item in this kit · 8 items

Hooks & beads

  • Standard dry-fly hook$132 × 25 · size 16

Thread & wire

  • Pale olive 8/0 thread$8.853 spools
  • Dark olive thread$3.251 spool

Materials

  • Other material: Barred Coq de Leon fibers, two, split$92 packs · From the recipe row "Tail"
  • White CDC$20.853 packs
  • Olive superfine dubbing$92 dispensers

Finishing

  • Head cement$5.951 bottle

Guide

  • Printed recipe and tying stepsIncluded1

Size 16 · Materials only · 144 flies

$152.55

$1.06 a fly

Bought separately $173.35 · you save $20.80

Includes Standard dry-fly hook · and 7 more

Every item in this kit · 8 items

Hooks & beads

  • Standard dry-fly hook$351 × 100 + 2 × 25 · size 16

Thread & wire

  • Pale olive 8/0 thread$26.559 spools
  • Dark olive thread$9.753 spools

Materials

  • Other material: Barred Coq de Leon fibers, two, split$22.505 packs · From the recipe row "Tail"
  • White CDC$55.608 packs
  • Olive superfine dubbing$184 dispensers

Finishing

  • Head cement$5.951 bottle

Guide

  • Printed recipe and tying stepsIncluded1

With vise & tools

Size 16 · With vise & tools · 12 flies

$184.60

$15.38 a fly

Includes Standard dry-fly hook · and 16 more

Every item in this kit · 17 items

Hooks & beads

  • Standard dry-fly hook$6.501 × 25 · size 16

Thread & wire

  • Pale olive 8/0 thread$2.951 spool
  • Dark olive thread$3.251 spool

Materials

  • Other material: Barred Coq de Leon fibers, two, split$4.501 pack · From the recipe row "Tail"
  • White CDC$6.951 pack
  • Olive superfine dubbing$4.501 dispenser

Finishing

  • Head cement$5.951 bottle

Tools

  • Rotary pedestal vise$791
  • Ceramic bobbin$141
  • Fine-point scissors$161
  • Whip finisher$91
  • Hackle pliers$71
  • Bodkin$51
  • Bobbin threader$41
  • Dubbing wax$41
  • Canvas tool roll$121

Guide

  • Printed recipe and tying stepsIncluded1

Size 16 · With vise & tools · 48 flies

$208.91

$4.35 a fly

Bought separately $219.90 · you save $10.99

Includes Standard dry-fly hook · and 16 more

Every item in this kit · 17 items

Hooks & beads

  • Standard dry-fly hook$132 × 25 · size 16

Thread & wire

  • Pale olive 8/0 thread$8.853 spools
  • Dark olive thread$3.251 spool

Materials

  • Other material: Barred Coq de Leon fibers, two, split$92 packs · From the recipe row "Tail"
  • White CDC$20.853 packs
  • Olive superfine dubbing$92 dispensers

Finishing

  • Head cement$5.951 bottle

Tools

  • Rotary pedestal vise$791
  • Ceramic bobbin$141
  • Fine-point scissors$161
  • Whip finisher$91
  • Hackle pliers$71
  • Bodkin$51
  • Bobbin threader$41
  • Dubbing wax$41
  • Canvas tool roll$121

Guide

  • Printed recipe and tying stepsIncluded1

Size 16 · With vise & tools · 144 flies

$284.55

$1.98 a fly

Bought separately $323.35 · you save $38.80

Includes Standard dry-fly hook · and 16 more

Every item in this kit · 17 items

Hooks & beads

  • Standard dry-fly hook$351 × 100 + 2 × 25 · size 16

Thread & wire

  • Pale olive 8/0 thread$26.559 spools
  • Dark olive thread$9.753 spools

Materials

  • Other material: Barred Coq de Leon fibers, two, split$22.505 packs · From the recipe row "Tail"
  • White CDC$55.608 packs
  • Olive superfine dubbing$184 dispensers

Finishing

  • Head cement$5.951 bottle

Tools

  • Rotary pedestal vise$791
  • Ceramic bobbin$141
  • Fine-point scissors$161
  • Whip finisher$91
  • Hackle pliers$71
  • Bodkin$51
  • Bobbin threader$41
  • Dubbing wax$41
  • Canvas tool roll$121

Guide

  • Printed recipe and tying stepsIncluded1

The creator

An illustrated portrait for Dekasso (an illustration, not a photograph)

Dekasso

@dekasso

Wherever the truck rolls to a stop.

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See everything by @dekasso

How it was made

1 iteration led here; the saved one is marked

  1. Iteration 1 of 11 Saved

Remixes

4 steps back

  1. Slate Ledge Grizzly Soft Hackle@dekasso · the original
  2. Grizzly Half Hackle Mayfly Dun@dekasso
  3. Evening Ember Sulphur Mayfly Dun@dekasso
  4. Thistledown CDC Olive Mayfly Dun — a fly pattern by DekassoThistledown CDC Olive Mayfly Dun@dekasso
  5. Slate Pool CDC Mayfly Dunyou are here

No remixes yet — make your own version.

Where this came from

“give it a two single strand split tail as is common with a mayfly... also make the wing look more disheveled”

fly pattern · made

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  • cdc dun
  • mayfly
  • dry fly
  • pale olive
  • split tail
  • coq de leon
  • trout
  • spring creek
  • white wing