I call this pattern the Iso Iso Baby not only because it’s supposed to represent a Isonychia dun but also because the basic idea of it was pirated or as we say in the industry “sampled” from another pattern– Doug Swisher’s Parachute Madam X or PMX. This pattern works well on it’s own and as a strike indicator when a dropper fly is attached. Here in the East anyway, Iso’s emerge starting in June and continue to do so through October. I think trout get so used to seeing them they'll take them whether there's a hatch on or not.
For a hook, a Dai-Riki #300 size 12 works well but even a 10 isn’t too big. After mashing the barb, get the hook firmly secured in your tying vise.
For thread, I’m going to use black 70 Denier Ultra thread but a medium grey or a rusty brown is also appropriate. Start your thread on the hook shank behind the eye and take wraps rearward and then break or snip off the tag. Leave the thread about 2 eye-lengths behind the eye. This will be the location of the wing post.
Snip a small clump of deer hair free from the hide. I like the stuff from right down the middle of the back. While holding the hair by the tips, strip out the lower, shorter fibers and fuzzies and organize the bundle for stacking. Place the hair, tips first, into your stacker and give it a good stacking. Carefully, get hold of the tips and remove the hair. Measure to form a tail about a hook gap and a half in length. Make 2 loose wraps of thread at the tie-in point to corral the hair and then pull straight up to tighten the wraps around it. Keeping a firm grip on the hair, start taking wraps rearward. The idea here is to keep the majority of the hair on top of the hook shank.
Continue taking wraps rearward to just above the hook barb, then back toward the eye to firmly secure the hair to the top of the hook shank. Pull the deer hair back and take a few wraps in front of it. Follow these with a couple wraps around the clump to begin the posting process. Although not essential, a small drop of super glue applied to the bottom of the post really works wonders to stabilize it.
First give the hair a mild twist to spread the adhesive and lightly bind the bundle. Then start making thread wraps up the bundle. You should find these tight wraps will set the glue and make the whole posting process a good bit easier. Trim the butts of the deer hair off to about a hook shank in length. This is just so they don’t get in the way, they’ll be trimmed further later.
Make open spiral wraps with your tying thread back to the hook point. For dubbing, I use a custom rabbit fur blend but use whatever isonychia dry fly dubbing you prefer. Create a fairly long, thin dubbing noodle on your tying thread. You really aren’t trying to build up a body here as much as color the thread. If you need more dubbing, add a small amount at a time. You want the abdomen to end with just a small space left behind the wing post.
For hackle, a medium dun looks real nice. Measure to find a feather appropriate for the hook size or slightly smaller. With the shiny side of the feather facing you, locate the point where the webby stuff starts and remove fibers to expose a half inch or so of bare stem. Then remove another 1/4 inch of fibers from just the lower side of the stem. This will aid in wrapping the hackle on the post.
Snip off the excess stem leaving about 1/4 of an inch for tie-in. Relocate your tying thread to just behind the eye and then secure the stem to the near side of the hook with firm wraps. Bend the stem up to vertical so it runs along the post and then lash it to the post with thread wraps. End with your thread just in front of the dubbing.
Snip a length of rubber leg material free from the hank. I’ve found that by folding one of these in half and cutting it at the mid-point, I have enough material to make two flies. I’ll then take one of the 2 segments and fold that in half. Once you get the 2 ends of the segment aligned, place it against the near side of the hook so the ends extend about halfway down the tail. Take 2 wraps of tying thread to bind it to the hook shank. Then, with your scissors, snip right at the midpoint of the loop you formed. Then reorient one set of legs to the far side of the hook and the other to the near side. With this procedure, you generally get nice even legs that don’t require further trimming. To ensure the legs don’t get jostled with subsequent wraps, pull the fore legs rearward and make full 2 wraps around just the hook shank.
To build up the thorax, create a short thin dubbing noodle on your tying thread. First use the noodle to cover the thread wraps over the rubber legs, then move forward to fill in the space behind the hook eye. Sweeping the rubber legs back makes this job easier. End with your tying thread positioned at the base of the post like so.
Get hold of the hackle feather and begin making wraps around the post. You can see how that little bit of bare stem really helped to get the hackle wrapping correctly. Keep making wraps one right under the previous all the way down to the bottom of the post. Then take 2 or 3 wraps of tying thread around the post to secure the hackle. Reach in with just the tips of your tying scissors and snip the excess feather off close.
Do a 4 or 5 turn whip finish on the post and make sure to snug it up real well. Then, snip or cut your tying thread free.
I like to trim the wing post so it’s about as long as the tail and resembles Vanilla Ice’s haircut. Head cement is your friend with this fly. A small drop applied to either side of the base of the wing post will work wonders in terms of durability. Although the rubber legs do add weight they also add a good bit of action and act as pontoons to stabilize the fly on the water’s surface. Applying a liberal amount of quality floatant ensures this already floaty fly will stay that way even longer.