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Thorax Dun

Thorax dun olive body dry fly pattern

Recipe:

Hook:14 - 22 Down or straight eye (Drennan Emerger or Teimco 101)
Thread:Olive or primrose 8/0
Tails:MIcrofibets dun or natural
Body:Fine olive dubbing
Hackle:Medium dun
Wings:Hen hackle tips

Uses:

The thorax dun is best in medium to slow flows where a low profile pattern is required. Used in mayfly hatches, it sits with the body on or in the miniscus and can often induce a strike where a heavier dressed pattern might be ignored. The version illustrated is great for olive hatches. Size is chosen to match the hatch. In winter, early and late season, Blue-winged Olive hatches can often require size 22s.

How to fish:

Fish using standrad dry fly tactics, maintaining a drag free drift at all times. This pattern is prone to sinking if fished in heavy broken water where a standard hackle or parachute pattern is more suited.

Tying instructions:

Right-handed tyers see below, left-handed tyers see alternative sequence »

1. Lightly wax and start the thread two and a half hook eye widths behind the eye. Take the thread in close touching turns toward the bend to create a bed on which to secure the wings. Return the thread to just forard of mid shank (approximately one third the length of the shank from the eye.
2. Select a pair of hen hackles and hold them so they curve away from each other.
3. Using a pinch and loop tie the hackle tip wings in place.
4. Make firm successive wraps of thread toward the bend.
5. Once secured cut the waste hackle material using a tapered cut to help produce a tapered body in the finished fly.
6. Complete tying in the hackle tip wings until the thread hangs down at the end of the shank.
7. Dub a short length of thread and with one of two wraps tie the butt end of the body. This 'ball' of dubbing will help separate the tails.
8. Take two of three microfibets and holding them diagonally across the shank and immediately in front of the dubbed butt, tie them in with one of two thread wraps.
9. Tie in a matching set of tails holding them across the shank opposite the preceding tails.
10. Complete tying in the tails wrapping the thread forward right up to the wings.
11. Cut away the waste ends of the microfibets and wrap the thread back to the bend ready to complete the body.
12. Twist the dubbing onto the thread to produce a thin rope.
13. Wrap the dubbing rope forward and stop two or three wraps behind the wing.
14. Tie in a hackle with its convex face toward the fly.
15. Now start wrapping the thorax using the same fine dubbing. Let the thread and bobin hang down and use your thumbnail to kink the hackle tips so they stand upright.
16. This will leave several unwanted hackle barbs pointing forwards over the eye.
17. Cut away the waste with a tapered cut.
18. Complete the dubbed thorax leaving enough room to tie off the hackle and complete a whip finish.
19. Make five or six wraps of hackle - two behind the wings and three in front, or three either side.
20. Tie off the hackle and cut away the waste.
21. Tie a thread head using a three or four turn whip finish and compete it with head cement.
22. Now using a fine pair of scissors trim away the hackle barbs from the underside of the fly. Your completed fly should look something like this.
23. From the front of the fly the hackle should look like this.

Notes

History: The original 'thorax fly' was designed and tied by Vincent Marinaro. The dressing illustrated here is based upon contemporary tying methods that have become the modern standard, popularised by tying experts like Skip Morris in his book The Art of Tying the Dry Fly. The hackle design is similar to those seen in the work of writers like John Veniard and Jim Birkholm.

Variations: Marinaro tied the original thorax fly. Sometimes called the Thor-X Fly, he tied the hackle criss-cross around the wing. This was intended to produce a realistic footprint holding the fly 'up on its toes'. Current thorax duns actually sit low on the water, 'down on their bellies,' by virtue of the cut away hackle barbs.

The colours can all be altered to match the hatch, and the materials should be chosen according to your own preference. The tails should be aprroximately the length of the hook and can be tied wih microfibets or hackle. The body should use fine dubbing. The wings traditionally are made using turkey flats, but hen hackle tips work fine. If you want a more opaque effect similar to turky flats, you can use feathers from the end of a hen cape - these will have to be prepared by stripping away the unwanted feather barbs.

Bibliography: The Art of Tying the Dry Fly, 1993, Skip Morris: US store, UK store. Fly Dressers Guide, John Veniard, third edition 1968. In the Ring of the Rise, Vincent C. Marinaro, 1976. A Modern Dry-Fly Code, Vincent C. Marinaro, 1950. Flies Only, (Section One to Ten), Jim Birkholm [Website » 30.03.2007]