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Thorax Style Sulphur Dun Pattern & Tying Instructions

Fly Tying Recipe: Thorax Style Sulphur Dun
1X-long dry-fly hook (e
g Dai-Riki #300), size 14
Yellow, 6/0
Matching pair of light-dun hen-back feathers
Dubbing ball:
Yellow beaver dubbing
8-10 stiff light-dun hackle fibers
Yellow beaver dubbing
Light dun
Yellow beaver dubbing
Wing burners
Show / Hide Thorax Style Sulphur Dun Transcript

Video Transcript:

In Vince Marinaro’s book “A Modern Dry-Fly Code”, he provided detailed instructions for tying a thorax-style dry fly. Few other dry fly patterns rival it’s ability to fool hyper-selective feeding trout. It’s finely shaped wings, tail fibers splayed at 90 degrees and criss-cross hackling all contribute perfectly to the fly’s look and function. They also make it rather difficult to tie.

Here, author, fly tier and blogger Matt Grobert is going to tie a sulphur version of Mr. Marinaro’s classic pattern. He starts by mashing the barb on a size 14 Dai-Riki #300 dry fly hook and then secures the hook in his tying vise. He loads a bobbin with a spool of yellow 6/0 Danville, yes, yellow.

Start your thread on the hook shank about 1/4 of the way back from the eye and take wraps rearward to the halfway point before snipping or breaking off the tag. Position your tying thread just slightly forward of the midway point on the hook shank.

For the wings, select 2 matching feathers from a light dun hen back. Although Marinaro used scissors to trim his wings to shape, Matt prefers wing burners for consistency. Unfortunately, this type are no longer made and are exceptionally difficult to find. With their front sides facing each other, clamp the two feathers in your wing burner so the stem runs straight down the middle of the form. Using a lighter, burn away the excess feather and then, with a bodkin, trace around the form to remove the larger burnt bits. Take the wings from the burners and strip off the fibers below the wing proper. This should leave you some bare stem to work with. Notice how the natural curve of the feathers makes them want to splay out.

Secure the stems to the top of the hook shank with a couple tight turns of tying thread. Make sure the bases of the feathers are located right at the established tie-in point. Once you’re satisfied with their location, take wraps forward to cover the butts and then take touching wraps rearward to the base of the wings. Pull the wings up and forward and make a wrap or two immediately behind them to bring them up to vertical. You can then work your thread back and forth between the front and the back of the wing base to strengthen it and keep the wings in an upright position. Now, take wraps rearward to about the hook point. With the smallest amount of dry fly dubbing, here, Matt’s using beaver because it takes yellow dye exceptionally well, form a small, thin noodle on your tying thread. Use this to create a neat little dubbing ball right where the hook begins to bend. Return your thread to just in front of the hook point.

8-10 stiff, light dun hackle fibers are used to form the tails. Strip the fibers free from the stem and align their tips by aligning the butts. Place the butt ends against the near side of the hook and take thread wraps rearward to secure them. Thread torque should carry them to the top of the hook shank. Split the fibers into 2 equal clumps, one on either side of the dubbing ball. Then, take thread wraps rearward to secure and splay them at a 90 degree angle. Once again return your tying thread to about the hook point. If there are any tail fibers that have gotten a little caddywhompus use just the tips of your scissors to trim them out. You can also remove fibers in order to get a roughly equal number on each side.

The same yellow dubbing as before is used for the body of the fly. This time, create a fairly long, thin noodle on your tying thread. Take wraps rearward so this dubbing merges evenly with the dubbing ball. Then, begin taking wraps forward to form the body of the fly. Additional wraps of dubbing in front of and behind the wing will help to further brace it. End with your thread just a short distance back from the base of the wings.

Take a very small wisp of the dubbing and this time create a short, thin, fairly loose noodle on your tying thread. Begin wrapping this loose noodle to build up a little ball at the base of the wing. Matt makes this look easy but trust me, it takes practice to get it right. End with your tying thread just in front of the ball.

Given today’s quality hackle, you’ll most likely only need a single, light dun feather to completely hackle the fly. Break or snip the lower part of the feather off to get rid of the webby stuff and then strip a scant 1/8” of fibers away from the stem. You want the hackle fibers to be slightly undersized for the hook. For this size 14, the fibers are just slightly longer than would be appropriate for a 16.

With the shiny side of the feather facing away from you, secure the stem to the top of the hook shank so the feather ends up on the far side of the hook. Continue taking thread wraps forward to just behind the eye in order to cover the butt end of the stem. With hackle pliers, get hold of the feather and come under the hook shank, behind the wing and over top of it in front. Carefully take a second wrap in this same manner and then bring the feather under the hook shank and up behind the wing. Next, carry it down and forward to under the hook shank in front of the wing. You may have to do a little coaxing and re-wrapping to get 2 complete turns in each direction shown. Notice how the hackle digs into the loose dubbing ball and stays in place quite well, even at a steep angle. With four hackle wraps made in total, bring the feather up in front of the wing and start taking thread wraps rearward in preparation for tie-in. Try not to trap the hackle fibers in the process. When you reach the hackle feather, pull it forward and take nice tight thread wraps to secure it to the shank of the hook. You can then reach in with the very tips of your tying scissors and trim the excess off close.

For the fourth and final time, get hold of a small amount of dubbing and create a short thin noodle on your tying thread. Wrap the noodle to produce a nicely tapered thorax at the front of the fly. You’ll very likely trap some hackle fibers while doing this, just snip them out so they don’t block the eye.

Finally, do a 5 or 6 turn whip finish, pull it tight and then snip or cut your tying thread free. No, it’s not the easiest dry fly pattern to tie but it’s one you want to have in your fly box when the trout get super picky.