The Joy of Fly Tying: Thorax Dun Mayfly

The second-to-last fly I teach in my Joy of Fly Tying classes is an adult mayfly imitation, and I'm not exactly sure who invented it. Or even how I came across it. It's a fairly straightforward tie that is easier than learning how to tie traditional upright wings, such as those on an Adams or a Light Cahill, yet it is a very effective fish catcher that can be just the ticket when trout are turning their noses up at your other offerings.

Size 14 Thorax Dun mayfly imitation.

This fly is called a Thorax Dun, and it can be tied in whatever color and size you need to imitate your local mayflies. In class I always teach it in a size 14, and usually in some kind of color combo that imitates a Sulphur or a Hendrickson mayfly. Or sometimes we tie it with a gray body and grizzly colored hackle, a sort of poor man's Adams, I guess you could say.

If you wanted to get fancy, you could make the wings out of turkey flats or some other feather, but I like to use Antron yarn, because it's easier to use and it has a nice shimmer. Perhaps some day the DuPont family will recognize me for all the times I have extolled the virtues of their synthetic yarns during my Joy of Fly Tying classes and lavish me with riches beyond my dreams... I won't hold my breath.

I now present to you the Thorax Dun, in video form:

Thorax Dun Pattern Recipe

Hook: Tiemco 100 or any other standard dry fly, size 10-22
Thread: 8/0 to match the body color
Tails: Dun or cream colored Mayfly Tails
Body: Superfine dubbing, color to match the natural
Wing: Antron yarn, looped straight up underneath the hook
Hackle: Rooster, sized for the hook, in ginger, dun, or grizzly