Last week, we featured a video lesson on tying an Isonychia Parachute, which imitates an adult insect, so here are the two previous stages—the nymph and emerger. Iso nymphs are active for most of the fishing season, which makes a nymph imitation a good searching pattern if you can’t tell what the fish are feeding on. These are predatory “swimmer” nymphs, which means that you don’t want to dead-drift them. Instead, use short strips to move the nymph from the middle of the current toward the bank. Trout will often chase down these speedy nymphs, which means that they don’t inspect the fly as much as they would a dead-drifting pattern, plus you don’t normally need to go with an ultralight tippet. Stripping or swinging this nymph through a run prior to an emergence can be very productive.
In this great video from Tightline Productions, Matt Grobert ties Vinnie’s Isonychia Nymph, named for his friend Vincent Caffarra, who developed the fly. As usual, Grobert, an author and blogger, demonstrates some useful tying tips. I especially like the way he protects the space behind the hook eye by wrapping the thorax dubbing rearward.
Vinnie’s Isonychia Nymph
Hook: 2X-long, heavy-wire nymph hook (here a TMC #5262), sizes 10-14.
Thread: Black, 6/0 or 140 denier.
Tail: Peacock herl, 3 swords.
Rib: Copper wire, small.
Back stripe (optional): Stripped quill of wood-duck flank feather.
Dubbing: Blended rabbit fur—2 parts claret, 1 part brown, 1 part black.
Wing case: Dark turkey-tail segment.
Thorax: Blended rabbit fur, as above.
Legs: Olive brown hen-back feather.
Head: Black tying thread.
Even though Isonychia hatches are generally sporadic, fish will often continue to rise even when just a few bugs are around. Isonychias usually hatch in the late afternoon or evening, and they spend quite a bit of time on the surface, which makes the emergers especially vulnerable to trout. That’s where patterns such as this one come in handy.
This version of the Isonychia emerger, also by Matt Grobert, is easy to tie, matches several mayfly species, and is durable. It imitates a mayfly struggling to escape from its nymphal shuck—just the kind of easy meal trout are always looking for.
Hook: 2X-short emerger hook (e.g. Dai-Riki #125), size 12.
Thread: Olive, 6/0.
Shuck: Brown Zelon.
Body: Isonychia-color dubbing.
Wing: Dun Comparadun deer hair, cleaned and stacked.
Head: Tying thread.