Thorax Dun

Thorax Dun


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 meniscus 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 standard dry fly presentation, 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. In some circumstances an effective alternative to Vincent Marinaro’s pattern is the Comparadun.

Tying instructions:

Left-handed sequence | Right-handed 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 complete 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.
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2 thoughts on “Thorax Dun

  1. The thorax dun should have the hackle wrapped at acute angles behind and in front of the wing…sort of in an X pattern.

    • Quite right Byron. That’s how Marinaro originally tied it. There’s a little more about the pattern in the right side bar. I wonder do you prefer the original tying..?