Although I've never personally witnessed a full blown isonychia hatch, here in the East anyway, they're around in lesser numbers from late May well into the fall and trout are almost always willing to eat them. Here author, fly tier and blogger Matt Grobert is going to tie an Isonychia Parachute using tying materials that complement each other exceedingly well and result in a pattern that's easy to tie, elegant and functional.
For a hook, Matt uses a nice, big size 12 Dai-Riki #300 dry fly hook.
Leaving some space behind the eye, he take wraps to attach his standard 6/0 olive Danviile to the hook shank and then breaks the tag end off.
White calf body hair is used for the post wing. Snip a small clump free from the hide and strip out the shorter fibers from the butt ends. Place the calf hair in your stacker and give it a good stacking to align the tips. These tips will point forward when they're tied in, so Matt orients the stacker accordingly and removes the aligned hair by the tips before getting hold of it with his left hand.
Measure the hair to form a wing post one hook shank in length and transfer that measurement forward to the tie-in point. With a pinch wrap, make two loose wraps of tying thread and then pull straight up. While still pinching the hair, continue taking wraps to firmly anchor it to the hook shank. You can then lift the butts up and snip them off close. Don't worry about making a fancy angled cut to help with body taper. Keep taking thread wraps forward before pulling the hair back and making a thread dam in front of it to keep it upright.
Now, starting at the base of the post, take a couple wraps just around the hair to get it roughly collected. Continue taking thread wraps to further post and stabilize the wing. The stronger you can make that right angle connection, the better. When you're satisfied with the result, take thread wraps rearward to in front of the hook point.
Moose body hair is used to form the tail and to build up the base of the abdomen. Snip a dozen or so hairs free from the hide and then snip away the off-colored butts. Stack the hair, this time pulling the tips out with your left hand and then getting hold of them with your right. Notice this is the opposite of what was done for the wing.
Measure the hair to form a tail a hook shank in length and then snip off the butts so they'll line up against the butts of the wing. You can see how this wonderfully simple technique forms a nice even underbody for the abdomen. With the moose hair secured, once again, end with your thread at the hook point.
For dubbing Matt uses his own custom rabbit fur blend that's 1 part burgundy, 1 part black and 1 part grey. It's really good looking stuff. Create a fairly long, slender dubbing noodle on your tying thread and then begin taking wraps so the dubbing starts right at the base of the tail. Continue taking wraps forward to make a nicely tapered abdomen that ends just at the base of the wing. Then make a single thread wrap right in front of the wing.
For hackle, Matt selects an appropriately sized feather from a medium dun neck. Although here he snips the lower portion of the feather off for video reasons, a feather of this length could be used to create two or even three flies. Strip about 1/4 of an inch of barbules free from both sides of the stem. Place the feather with the shiny side facing upward against the near side of the hook and take thread wraps around the bare stem in front of the wing post. Make sure the stem is well secured directly to the hook shank before raising the feather to vertical and taking wraps to attach it to the wing post. Finish with a single wrap around the hook shank.
With a small pinch of the same dubbing, create a shorter, thin noodle on your tying thread. Wrap the dubbing noodle around the hook shank to fill in the space in front of the wing post and build up the thorax of the fly. A few wraps back and front will help to further stabilize the post. End with your thread on the near side of the hook in front of the wing.
Get hold of the hackle and begin taking clockwise wraps around the base of the wing post, 5 or 6 turns ought to do it. Pick up your bobbin and make horizontal clockwise thread wraps to secure the hackle tip to the post. Be careful not to trap hackle fibers while you're doing this. Again, end with your thread in front of the wing on the near side of the hook. With fine pointed tying scissors, reach in and carefully snip the remaining hackle off close.
With your whip finish tool, whip finish around the wing post as opposed to the hook shank. This orientation for a whip finish may seem awkward at first but is really fairly easy to do with a bit of practice. With your tying thread secured, you can cut or snip it off close to the wing post.
Although this fly works great on it's own, it also works very well as an indicator when placed in front of smaller offerings.