FLYMPH FORUM

Well this thread was going to feature photos of two flies that I am trying to use to imitate Isonychia nymphs. Sadly when I set out to shoot them, my camera's battery was dead, and the charger suddenly wouldn't charge. So a written description must suffice. One section of one of my favorite streams has relatively sporadic but steady evidence of these bugs. Their shucks are often found on the stream edge rocks. These are large specimens, approaching an inch. They seem to lack the white back stripe of a typical Bicolor. I have tied up two versions. Version one is merely a wire ribbed pheasant tail soft hackle with a PT tail, and short partridge hackle behind a brown metal bead for a head. The second version uses brown ostrich herl for the body, with a wire rib over wrapped weight, the tail is a few ostrich herls left rather short. with a brown hen hackle at the head. Here is a quick and dirty photo of a few shucks I found early last fall.


Any thoughts on how to better imitate these bugs?

One of my favorite bugs when I fished the Beaverkill & Willowemoc regularly. My imitations always emphasized the dorsal stripe and the very prominent (when viewed in the water) gill structiure. My favorite pattern (a lot of parts but easy to tie) was/is:

Hook: Mustad 9671, #10
Thread: Black 6/0
Underbody: two lead strips approx .020, tied parallel to the shank, overwrapped with thread and laquered
Tail: peacock herl, 3 strands, tied short (about as long as the hook gape)
Abdomen: Peacock herl
Rib #1 (gills): Light brown ostrich herl, closely wrapped
Dorsal stripe: stripped ginger hackle stem,
Rib #2: fine gold wire, counterwrapped over gills and dorsal stripe
Thorax: Peacock herl, same diameter as abdoment
Wingcase: Mahogany turkey tail heather segment
Dorsal stripe (over thorax): Continuation of stripped ginger hackle stem
Legs/Hackle: Grizzly hen tied as a collar, slightl undersized for the hook; "think 14"

This pattern worked for me in the Catskills and Poconos as well as in the upper midwestern streams. It was developed after considerable observation of Iso nymphs in an aquarium enviornment. I fish it both dead drift, twitched and stripped. It is not a true softhackle or flymph, but it does employ a softhackle as the collar. Sorry no pics because I have none of the flies available as I seldom fish water with Isos present anymore.

EP

The wing pads do seem to be quite prominent on these guys, and I suppose, even more so as they are preparing to emerge. I tried to keep things in the round as it where, but it may be a necessary addition. I wasn't able to find a live specimen, but online photos of live ones showed the prominent gills as you say. That is what drove me towards the ostrich for the body. I hadn't thought of it as a rib. If I may ask, why the peacock for such a dark brown insect? Any reason other than peacock herl just works?

If I may ask, why the peacock for such a dark brown insect? Any reason other than peacock herl just works?

Nope -- other than the Leadwing Coachman being, in the eyes of many, the prototype Isonychia imitation. I simply started using it in this particular context because peacock herl nymphs worked well for me in the Catskill rivers before I started tying an Iso nymph deliberately. When I began experimenting with various Iso ties, including dark brown dubbed bodies and the ever popular claret dubbed bodies, the peacock was the most productive.

EP

Eric,
Thank you for taking the time to explain. The waters I fish are in the northern foothills of the Adirondacks, so I expect the the bugs are pretty similar. I will give your recipe a workout in a few weeks.

I will give your recipe a workout in a few weeks.

Don't be afraid to tie them nice and full. The lead flattens the body, so you can make the peacock pretty thick. Let me know how they work.

Eric

Will do.

I still use this pattern, but tie the tail shorter than shown. It works well with the hackle a bit longer for adults. In my area, the color of the adult body is actually a dark reddish brown, and while this pattern calls for a mahogany body dubbing, you could use the appropriate color for the naturals you see.

You can also add the center stripe down the back if you desire. I do sometime using silver sewing thread for this.

Here's the dressing:

Hook: Standard long shank nymph hook #12-16

Thread: Dark brown

Hackle: Brown Partridge

Tail: Black maribou fibers

Body: Blended brown, black and red rabbit dubbing to result in a mahogany color

Thorax: Peacock herl

Mark

Great pattern, Mark. Is there a peacock herl thorax on this fly?

Here is something I have wondered about. The Iso nymphs are strong swimmers, and sort of wriggle as I understand. I have seen a number of flies that use a curved hook to emulate their motion. I have wondered about a marabou tail to simulate the undulation of their swimming action. This is why I used ostrich for the tail on one of my attempts. I wonder if an appropriately sized/colored Murray's strymph would be a decent imitation. Certainly would qualify as a wingless wet, though maybe not in a traditional sense.