This is a March Brown dry fly tied Catskill style by author, blogger and fly tier Matt Grobert. Here in the East anyway, it's a classic pattern that still fools trout during one of the quintessential mayfly hatches.
Matt starts his March Brown with a throwback Mustad 94840 dry fly hook in a size 12. For thread he's loaded a Rite Half Hitch Mag bobbin with a spool of olive Danville 6/0 tying thread.
Start your thread on the hook shank leaving a hook eye length space behind the eye and take wraps rearward before snipping or breaking off the tag.
Cut the tip from a single wood duck feather. To keep the wings slender and neat, you may have to strip a few extra fibers from the butt of the feather. Squeeze the two sides together which should align the tips. Measure the fibers to form a wing about a hook shank in length and then transfer that measurement forward to the tie-in point. In classic Catskill style, Matt likes to leave a fair bit of room between the hook eye and the base of the wing. Reach in with your tying scissors and snip the butt ends of the wood duck off at an angle to form a little ramp leading down to the hook shank. Make thread wraps to build a small dam in front of the wing and push it up to nearly vertical.
Separate the wood duck fibers into 2 equal clumps then cross your thread diagonally from front to back between the two clumps. Get hold of the far wing and bring your thread between the two wings and around the base of the far wing before finally bringing your thread back between the wings. Go behind the near wing and then wrap around the base of that wing and back through between the wings - this is a figure 8 wrap. Take a single wrap around just the hook shank to, essentially, save your work. Keep making figure 8 wraps until the wings are well angled and separated, usually 2 or 3 is enough. With the wings looking good, take wraps rearward down the little ramp to the hook shank and rearward again to about the hook point.
For the tail, strip about 1/8th of an inch of fibers free from the stem of a long brown hackle feather, doing your best to keep the tips aligned. You can adjust the butts if necessary. Measure the fibers to form a tail approximately a hook shank in length and then snip the little curlies off square. Secure the fibers to the top of the hook shank with a few good wraps then pull slightly upward on the tail as you take more wraps rearward to just before the hook bend. End with your tying thread at about the hook point.
Take a small pinch of fawn colored rabbit fur dubbing. This color imitates the more visible lighter underside of the abdomen of an adult March Brown. With the rabbit fur, form a slender dubbing noodle on your tying thread. Take wraps so the dubbing starts right at the base of the tail and then make adjacent wraps forward up the hook shank. Try to make the body even and slightly tapered, increasing in diameter from back to front. Ideally, the dubbing should end so there's some open space behind the wing.
Select appropriate sized brown and grizzly hackle feathers and lay them so the dull or backsides of the feather are facing each other. Matt likes to place the grizzly hackle on top of the brown so he can control the final hackle color by how many wraps of grizzly hackle he makes. Tie in both hackles at the same time behind the wings on the near side of the hook. Take a few good wraps to secure them behind the wing and then a few more in front to bind down the butts. Notice how much bare shank Matt has left behind the hook eye. Be sure to get hold of the brown hackle first. Make a full wrap behind the grizzly hackle and then two more behind the wing, end with two more wraps of hackle in front of the wing. Secure the hackle tip with a few tight turns of tying thread and then carefully reach in with your scissors and snip the tip off close.
You can then get hold of the grizzly hackle and begin making wraps around the hook shank, zig zagging so as not to trap fibers as you go. Two wraps behind the wing followed by two in front is generally enough to form a nice blend of brown and griz. Again, secure the hackle tip well and then snip it off close, doing your best not to snip your tying thread or too many extra hackles in the process.
Finally do a 5 or 6 turn whip finish and then snip or cut your thread free. And that's a classic Catskill-style March Brown Dry. Matt will often replace the brown hackle fibers with moose body hair which makes for a really exceptional looking fly.