Isonychia Beaver

Wets, the subtle art form where masters are few and far between.
letumgo
Posts: 65
Joined: Sun Feb 13, 2011 1:08 pm

Isonychia Beaver

Post by letumgo »

Isonychia Beaver
Hook - Daiichi Model 1710/Size 12
Thread - Pearsall's Gossamer Silk (Gold/6A)
Hackle - Indian Hen Saddle (Ginger Speckled Brown)
Tag - Three Wraps of Pearsall's Gossamer Silk (Gold/6A)
Abdomen - Beaver Dubbing (Isonychia)
Thorax - Peacock Sword Fibers (Natural Metallic Blue)
Head - Pearsall's Gossamer Silk (Gold/6A) coated with Sally Hansen's "Dries Instantly" clear nail polish
Isonychia Beaver Soft Hackle.JPG
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I bought this dubbing at a small shop in the Adirondacks. It has a wonderful blend of dark red/claret/brown. The dubbing is made by a company called Mad River Dubbing Company (http://madriverflytyingmaterials.com/Home_Page.html) located in Verona Beach, NY. I have no affiliation with this company, so don't look at this as an advertisement. It was just such a great dubbing color, I wanted to share the source with you guys. The dubbing is very nice material to work with.

I used five long (~ 1.5" to 2")peacock sword fibers tyed in by the tip. I then grasp all of the sword fibers, by the base of the stem, in a hackle pliers. Then twist the sword fibers together and wrap them forward, forming the thorax of the fly. The sword fibers seem to be a bit tougher than peacock herl, so I decided to skip the dubbing loop. If I wanted to reinforce the thorax a bit more, I would probably add a drop of cement to the hook shank before wrapping the sword fiber over it.

There are two main reasons I did not use a dubbing loop method to reinforce the peacock sword fibers:
1) Cosmetics - I did not want the light color silk showing thru in the thorax area
2) Mechanics - Sword fibers are fairly short, so it is harder to neatly form the dubbing loop and still have enough material left to wrap the thorax. I find that the material gets somewhat shorter when you twist it in a thread dubbing loop. This is not a problem with peacock herl, due to the longer length. Peacock sword stems just tend to be shorter and thus a little different to work with.

Isonychia Nymph
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Hook - Daiichi Model 1710 (Size 12)
Thread - Pearsall's Napels Silk (Antique Gold /31)
Tail - Burnt Turkey Tail Fibers (Natural)
Lateral Line - Twisted Dubbing Loop formed using the tying silk (tyed in at both ends and the middle)
Body - Beaver Dubbing (Isonychia color)
Legs - Burnt Turkey Tail Fibers (Natural)
Head - Pearsall's Napels Silk (Antique Gold /31) - darken top side with a brown sharpie to complete the fly. The photo was taken before I darkened the head of the fly.

Notes About the Isonychia Nymph Pattern Design:
The Isonychia bicolor nymph is noted to be a very powerful swimmer. For this reason, I tyed the fly with a longer tail, in hopes that it will allow greater movement of the fly in the water. I know the natural insect only has three tail fibers, but I haven't met a fish who can count, so I ignored this fact.

The tail and legs are all formed using natural turkey tail, which has been "burnt" in a dilute bleach solution to remove the tiny barbules that hold the fibers together. I chose this material since it had similar markings to the natural insect (mottled) and it had a similar shape (wide flattened) to their legs. I clipped off the fine ends of the fibers to get the width I wanted. The legs were formed by tying in the turkey tail fibers by the thin end (to allow greater movement).

I noticed that the tail fibers have a bit of a red cast to them and the head of the fly is dark like the body. Once the fly was finished I added these colors with sharpie markers. You can fine-tune the color combination based on local insects.

The lateral line is formed by making a dubbing loop using the tying thread. To form the lateral line, I dubbed the rear half of the body of the fly and then twisted the silk dubbing loop into a tight cord and pulled it over the back of the fly. Tye the dubbing loop in at the middle and then pull it back out of the way while you form the front half of the fly. Once the thorax and legs are all in place, twist the dubbing loop and pull it over the front half of the body. Secure the dubbing loop and then whip finish a head.

I think the body of the fly needs to be just a bit plumper. The natural insect appears to have more of a plump cigar shaped body. The body shape can easily be adjusted by forming an underbody, or using a bit more dubbing.

NOTES ON FISHING ISONYCHIA PATTERNS

I do not having direct experience fishing this insect and as a result I had to do research in a few of of my fly fishing books. Here is what I have learned so far:

Source 1 ("Fishbugs" by Thomas Ames / ISBN 0-88150-675-3 / Page 63) - Mayflies of the genus Isonychia hatch throuout the summer in many parts of the Northeast, with especially strong emergence periods in June and again in September on into October. It is one of the few mayflies that hatch out of the water, although it is perfectly capable of emergence in the conventional manner and will hatch on the water's surface in the early season when the rivers are high. By late summer their split nymphal cases begin appearing by the dozens on the sides of stone flies a few inches above the water line. The early season adults are quite large and as dark as bittersweet chocolate, with creamy patchs in their slate-colored wings. By autumn they have diminished in size, their bodies are lithter, and wings more uniform. Isonychia have several peak hatch periods in a single season. Those that hatch directly from the water, or that are blown onto it after hatching seem to have as much difficulty with liftoff as an albatross. As they vigorously flap their wings, the whet the appetites of fish not previously disposed to feeding on the surface. A trout that charges impulsively up through the surface to chase a choise entree on the verge of escape is nature's equivalent of the Polaris missle. The species name comes from the distinct difference in shade between the dark ginger forelegs and the cream-colored second and third pair of legs. The tips of the insect's forelegs are also light, as if it were wearing gloves, and it holds them out like a carriage driver, for which it has earned the nickname leadwing coachman or, in the spinner stage, white-gloved howdy.

Source 2 ("Nymphs - Volume 1" by Ernest G. Schwiebert / ISBN 978-1-59228-499-3 / Pages 91, 271, 277-80, 281 - 284, 288, 472, 597 n2 / Selected passages only):

Mature adult Isonychia mayflies can be in the 15 to 18 millimeter lenghth range (mahogany bodies and chalky tails)

Eggsacks on the females will be dark olive (like tiny canned peas)

Isonychia bicolor nymphs are dark and have a pale median stripe on their thoracic carapaces. In some nymphs, the strip will not be continuous over the length of the back. The color of the strip ranges in color - dark ginger or ochreous case in some specimens.

Isonychia bicolor may differ in size, color, and silhouette depending on the fishery it is collected from, the pH of the stream, and degree of pollutants in the water (lesson - important to know what the local insect looks like to create a better immitation)

I (Schwiebert ) believe that the pale dorsal median stripes on our Isonychia nymps are triggering clues, and our trout forage on them throughout the season, beginning with the rapidly maturing nymphs of spring, to the much smaller, darker-bodied nymphs in October. The discrete axial strips of each species are important in designing effective imitations, because they will vary.

Schwiebert used the stripped center quill of a gray partridge feather to simulate the dorsal strip of the nymphs. He mentions that the stripped quills are delicate at their tips and much wider at their butts, in perfect simulation of the axial chalk-colored body stripes on the easter nymphs. The strips are thin and indistinct at their terminalia (tail), increasing in width until they are generous at the thorax. Mottled legs are imitated with several turns of dark brown-mottled partridge.

Mature Isonychia nymphs sometimes engage in surprising pulses of schooling behavior, and that during such migrations, large numbers gather in the rocky shallows before they hatch.

Isonychia nymphs are photophobic (lesson - fish in the early morning/late afternoon or in shaded areas) and become most active at marginal levels of light, and their mature nymphs are often schooling then. Schwiebert chose to fish the imitation at first light. He mentions fishing the runs slowly, in a series of parallel lines of drift, while working patiently upstream. He used imitations tyed on size 8 and 10 hooks (no make or model listed) and used unweighted patterns so he could work the shallow areas. The weight of the hook was enough to get the nymphs down and fishing in such shallow water. He mentions beginning fishing in the shelving depths offshore, casting a bit longer at first, and shortening each successive cast until fishing the shallow line of drift nearest the bank. Each parallel line of drift was approximately 2 feet apart. Watch closely for any pause in the drift and tighten the line.

Mature nymphs range between 9 and 18 mm in length, excluding their caudal filaments (tails). Axial stripes ranging from rusty ginger to chalky white are present on the dorsal surfaces of most Isonychia specimens, but these are not always contiguous, and their placement and length.

The gill plates (along the sides of the rear part of the nymph) are tightly closed while the Isonychia nymphs are swimming, to accentuate their smooth, fusilliform bodies. (lesson - I interpret this to mean that it is not important to include the gill plates in the imitation)

Mature nymphs prosper in the swiftest of the boulder-broken currents, and their restless agility and energy can be quite astonishing. THey are the true circus acrobats of the entire mayfly clan. Most seam to relish the tumbling spume, seaking sheltered refuge in narrow crevices and in the shadowy intersticies between stones inthe bottom cobble. High concentrations of dissolved oxygen are apparently critical to this genus.

The nymphs are unusually restless and active. Locomotion is accomplised with surprising vigor, in a kinetic series of restless little starts and bold spurts, and such swimming behavior suggest a somewhat erratic retrieve in fishing imitations of the Isonychia nymph.

(lesson - The nymphs are powerful swimmers and most likely to be found in areas with tumbling currents/heavy current/high oxygen levels. Fish the nymph with and active erratic start/stop retrieve. It will be important to use an open-loop knot to maximize the movement of the fly. An "S" shaped hook may be best representation of the nymph, especially if tyed in the round - soft hackle style).

I am sure others can provide additional first hand information, but hopefully this is a start.

Additional note about Schwiebert's book (volume 1) - Initially I found the size of the Nymph books intimidating, but have found that the text is very well written and enjoyable to read. I can see why these books have become such a classic reference work.
Last edited by letumgo on Thu Feb 17, 2011 9:13 pm, edited 1 time in total.

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Eperous
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Re: Isonychia Beaver

Post by Eperous »

Good looking flies... ;)

Iso's can be found on lots of Catskill streams; on the Esopus Creek Isonychia are "the hatch" of the season... I'm fairly sure that there are two different broods/species - I'm no bug guy by any stretch - but those that appear for a short period in late May - early June appear much larger in size than those that reappear sometime in August and last through early October, in a good year.... most wet flies/nymphs with peacock herl - like Leadwing Coachmans - are excellent choices to fish submerged... Iso's are very easy to identify as they swim to rocks and their shucks can be found all over... on a good day on the Esopus, thousands of shucks will line the edge of the stream...

Your flies will/should catch trout if fished properly... I would suggest high in the water column, with a twitch - or short strips back to you...

You might want to check these nymphs out also, though I tied them on a size 12 work when I meant to use a #10...

viewtopic.php?f=4&t=1272

You also mentioned "the man", Ernest Schwiebert... here's my interpretation of his Isonychia Nymph, based upon Matching the Hatch... ignore, the Jennings' Isonychia Nymph that I tied with antron in this thread, I gave all those away when CJ set me straight and put me on to a source of seal fur..

viewtopic.php?f=4&t=431&hilit=+Isonychia

And, here's what real nymphs look like... when you see these, you had better be fishing something, and hold on tight...

Image

Nice ties, and good fishing this season...

Ed

redietz
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Re: Isonychia Beaver

Post by redietz »

Those look great. The only thing I'd change would be to use a darker brown hackle.
Bob

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Joe Fox
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Re: Isonychia Beaver

Post by Joe Fox »

Good read.
Isonychia are one of the few nymphs what are always good to fish. Due to the fact they are swimmers they are always around, where many nymphs are well hidden till their emergence. Fishing size 16's months before the hatch can be very effective.

As for this isonychia hatchs only on rock, they may want to hatch on rocks but far too often they are unable to get there. They may get to the surface quickly, and even split their shell fast but they say on the surface for quite sometime before they lift off, offering a large, easy meal to trout.
During hatches wets are wicked (yes I said wicked) good. The swing seems to mimic their swim to the rocks the wish to hatch on.

The first hatch, the big iso as we call it, it often over shadowed by March Browns & the Drakes, but can still provide fantastic fishing. The summer iso, a little smaller then the early one, can provide amazing fishing between the various sulphurs. As the summer progresses iso hatches come and go in mixed quantities. The Fall iso, even small then the summer one and around a size 14 2XL, also provides big bug activity when there can be none.

Joe

letumgo
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Joined: Sun Feb 13, 2011 1:08 pm

Re: Isonychia Beaver

Post by letumgo »

Bob - Agreed. I have tyed some with English Grouse wing hackles and love the look of the rich brown/black mottling. I think it would match the naturals very nicely, and compliments the coloration of the body.

Thanks for the welcome Ed and Joe! Thanks for the wonderful links. This is a very impressive & educational website.

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Eperous
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Re: Isonychia Beaver

Post by Eperous »

letumgo wrote:Bob - Agreed. I have tyed some with English Grouse wing hackles and love the look of the rich brown/black mottling. I think it would match the naturals very nicely, and compliments the coloration of the body.

Thanks for the welcome Ed and Joe! Thanks for the wonderful links. This is a very impressive & educational website.
Ray, you might want to consider adding a tail to your Iso wets - a dark one at that... I believe it's a very predominate feature on these mayflies... but, as I said up top.... nicely done...

Ed

letumgo
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Re: Isonychia Beaver

Post by letumgo »

Ed - Here is a wiggle-tail soft hackle version of the Isonychia nymph pattern show above. This version was tyed on a Mustad R50 hook (size 14), and the hackle is English Grouse Coverlet feather (rich mottled brown color). Can't wait to give these a swim this spring.
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redietz
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Re: Isonychia Beaver

Post by redietz »

Yes!
Bob

Snowmass Angler
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Re: Isonychia Beaver

Post by Snowmass Angler »

Letumgo, those are extremely cool!

major257
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Re: Isonychia Beaver

Post by major257 »

Ray,

Did you find that dubbing locally up home here in North Creek?

Matt

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