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  1. #1

    Default slate drake (Isonychia)

    I'm planning a trip to Rocky Fork Creek in TN and wanted to tie up some Slate Drake's. Never tired them before. Anyone have a good pattern? Would especially love a TN native view on this fly??? Thanks for any help


  2. #2
    Join Date
    Jun 2008

    Default Re: slate drake (Isonychia)


    This is one of my favorite hatches. I usually carry 4 specific patterns- a nymph, (Iso Nymph) 2 duns (Iso Comparadun and Dun Variant) and a spinner (Iso Compara-Spinner), but a lot of other stuff you probably already have will work too. Isonychia (aka Slate Drakes, Mahogany Drakes, White Gloved Howdies) are actually at least 2 species. Up here we get a size 12 in early summer and another hatch in the fall a little smaller at 14. Just check on the sizes of the critters in TN before you tie up a ton if you can.

    Isonychia Nymphs-
    Good general patterns you may already have are Prince Nymphs, Zug Bugs and dark brown hares ear Nymphs. The nymphs are good swimmers, so you can actively fish these with short quick strips, or dead drift them. Isonychia nymphs have a distinctive white stripe that runs down the middle of their back and fringy tails. If you want to tie up a specific pattern this one is great:

    Isonychia Nymph (Loren Williams version)
    Hook: Mustad 9672 10-12 (i just tie them in 10-12 even though the fall version of the nymphs is slightly smaller)
    Weight: .015 lead wire or lead substitute, wrapped around the shank
    Thread: Brown 6/0
    Tail: 3 Pheasant Sword Fibers ½ body length
    Rib: monofilament (I use wine colored wire)
    Dorsal Vein: Cream Hackle Stem ( I just use 3/0 white thread) over abdomen and thorax and held in place by ribbing
    Wingcase: Turkey Tail with a white strand of hackle stem (or thread) down the middle
    Abdomen/Thorax: Dark reddish brown dubbing (80% Black dubbing, 20% Reddish Brown Rabbit)
    Legs: Brown Partridge (or brown hen)

    Emergers: Isonychia are one of the few mayflies that often emerge like stoneflies. The nymphs tend to crawl out onto rocks in, or just below, fast water sections, and then shed their cases and turn into the winged duns. Look for the empty cases on rocks to let you know whether hatches have been taking place. Since they don’t emerge in the water very often, I don’t fish emerger patterns much for this hatch, but I have had some luck swinging the classic wet pattern Leadwing Coachman down and across. Not sure if fish take them for emergers or drowned adults, but they are a good pattern to try as a general searching pattern, or if the fish are not taking dries during an Iso hatch. The Leadwing Coachman is also an excellent “caddis pupa” pattern if you get a Grannom Caddis hatch, so it’s a good pattern to have in your box.

    Leadwing Coachman Wet
    Hook: Wetfly, like a Mustad 3906B size 8-10. Even though this is a big wet, it seems to work fine
    Thread: Black
    Tail: None, instead a “tag of gold tinsel

    Body: Peacock herl
    Wings: Lead colored starling or duck quill slips
    Hackle: Brown Hen

    Duns- Because a lot of the "hatching" takes place on rocks, duns often aren't as available as the spinners. Still, a lot do get blown in the water, so there is often some action on duns. A lot of times anything dark bodied, with dark wings around a size 14 will work- Adams, Dark Hendricksons/Red Quills etc. If you want to tie some up specifically for Isonychia, I use these guys:

    Isonychia Comparadun
    Hook: Dry fly 12-14
    Thread: Rusty Brown 8/0

    Tail: Dark Dun Microfibbets
    Abdomen: Dark Brown Dry Fly Dubbing or Mahogany Goose or Turkey Biots, tied in “ribbed” rather than smooth
    Thorax: Mahogany Brown Superfine or other dry fly dubbing
    Wing: Dark Gray “Coastal” or “Comparadun” Deer Hair

    Dun Variant (these are my favorite to fish for this hatch because you can skitter them around on the surface, like the naturals seem to do.)
    Hook: Standard dry fly 10-14 (I prefer a short shank dry fly hook like the Mustad R48 or TMC 921 size 12. This seems to match both early summer and the smaller fall hatch very well)
    Thread: Brown
    Tail: Dun Hackle barbs (or long Coq de Leon Medium or Dark Pardo barbs)
    Body: Rhode Island Red Hackle stem (Dark reddish brown stripped quill stem, or dry fly dubbing)
    Wing: None
    Hackle: Dark Dun collar, I like using oversize hackles on these to skate them around, so a size 12 on a 14 hook.

    Isonychia Spinners- Again, patterns like a 14 Rusty Spinner will do the trick here, but a better match for them IMHO would be the Iso Compara-Spinner.

    Isonychia Compara-Spinner (tied "Variant" style)
    Hook: Dry fly 10-14 (I prefer a 3 extra fine standard hooks and just tie them in 12-14 )
    Thread: Rusty Brown 8/0

    Tail: Dark Dun Microfibbets or coq de leon medium Pardo. I don’t split the tails on these because I like to skitter them.
    Abdomen: Dark Reddish Brown Dry Fly Dubbing
    Wing: None
    Hackle: Light Dun, oversize, (size 10 hackle on a size 12 hook). I leave these tied “in the round” to skitter on the surface. They can be trimmed on stream with a pair of scissors by cutting an inverted “V” on the bottom to sit lower in the water, but still be easy to see at dusk, or trimmed on both top and bottom to sit flush in the film. This is a very effective pattern for Isonychia since a lot of the action is on spinners.

    Simple Poly Wing Isonychia Spinner (A simple, inexpensive tie, but not as fun to fish, at least for me)
    Hook: Dry fly 10-14 (I prefer a 3 extra fine 12-14)
    Thread: Rusty Brown 8/0

    Tail: Dark Dun Microfibbets or coq de leon medium Pardo tied split
    Abdomen: Dark Reddish Brown Dry Fly Dubbing
    Wing: White Poly, tied spent
    Hackle: None

    Good luck, I hope some of these work for you!


  3. #3

    Default Re: slate drake (Isonychia)

    Thanks. That helps a lot. I knew I'd have some prince nymphs, and wasn't going to worry about emergers. Probably tie up some spinners and leadwings. .
    Thanks a lot.

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