This Size 16 fly is a BWO Emerger. The pattern has an elk hair tail. The abdomen is constructed of dark gray thread with a fine dark olive copper wire ribbing. The thorax is a three part combo: of dark olive Superfine dubbing; one strand of Krytal flash folded over four times to make a bunched emerging wing and a dun hackle. You will notice the hook is not a curved, which has become the norm for many emerger/stillborn/cripple patterns.
The above thorax should be tied as follows: start a small amount of dubbing for the rear portion of the thorax, then tie in a hackle by butt section. Wrap two to three turns of hackle but do not advance too far forward toward the eye of the hook. You need to allow room for the emerging wing and the remainder of the thorax, as well as the thread head. After the few turns of hackle, take one strand of Krsytal Flash and fold it over four times to form a compact wing bud. It should not extend back past the mid point of the shank.Tie it in and cut off the excess. Finish the thorax with the dubbing and a tidy thread head. I used 6/0 thread for the abdomen. For the remainder of the fly 14/o was used.
This one has a loop wing. The tail is still elk hair; the body is the same dark gray 6/0 thread with dark olive wire. I dubbed a wrap of olive Superfine then I tied in the strands of Krystal Flash and pulled them to the rear. This time the hackle was tied in and two wraps were made and tied off. Then I pulled the Krsytal Flash strands over the top of the hackle and tied off. The thorax was finished off with dubbing and then a thread head. I think either version is acceptable for an emerger. The tail could be deer hair, synthetic fibers, moose hairs, guard hairs. The key here is the Krystal Flash wing bud or wing loop. The effort is to create the emerging wing. This pattern would lend itself to a size 18 as well. Also, all the components/colors of the above pattern can be changed to represent other mayflies.I use the Superfine Dubbing because the fibers are, well super fine, so they twist onto the thread to form a very narrow coating upon the thread and allow for a small dubbed body.