Thursday, August 15, 2019

Paul's September 2019 Fly of the Month

Preston Jennings' Isonychia Nymphs



Preston Jenning’s Isonychia Nymph
Hook:  Size #8, #10, or #12 nymph hook.  Jennings used both sproats and snecked hooks, but a 1 x-long or 2 x-long hook will work.
Tying thread:   Black, 6/0. 
Tail:  Tips of a Partridge feather.  (You can also substitute with Pheasant Tail fibers,     but my favorite tail is 3 Peacock Sword fibers.)
Rib:  Round gold tinsel.
Abdomen:  Seal’s fur (or substitute) dark red and plum, mixed.
Thorax:  2-3 strands of Peacock herl.
Hackle:  Furnace cock hackle, two to three turns.

           Preston Jenning’s Isonychia Nymph Variation
Hook:  Size #8, #10 or #12 nymph hook. 
Tying thread:   Black, 6/0. 
Tail:  3 fibers of Peacock Sword.
Body:  Seal’s fur (or substitute) dark red and plum, mixed. (There is no Peacock Thorax or rib on this version). 
Hackle:  One to two turns of grouse for the hackle.

This is a very traditional and old trout pattern.  Tie and fish it and you’ll be stepping back into Fly Fishing History.  It was developed by a fly fisher named Preston Jennings.  In his day, Preston Jennings was a very well known fly fisherman and tyer.  His book “A Book of Trout” was published in 1935.  It was the first comprehensive guide to the insect life that trout feed on and the patterns that would emulate them.  The book was the first of it’s kind back then and the gold standard by which future books would be measured.   Jenning’s home waters were Catskill Rivers, especially the Esopus Creek.  He was one of the most innovative fly tyers of his time.

Isonychia Nymphs are not like other mayfly nymphs which seek cover on river bottoms.  They are active swimmers.  Often darting from rock to rock even in fast water.  What’s great about fishing these nymphs is their larger size.  Also, their availability from May into October.   

Jennings tied his iso nymphs in a couple of different ways and materials.  I like to tie his ‘traditional’ pattern and tie a lot of them with peacock sword tails (a component of his variation).  What’s great about fly tying is experimenting for what works best for you.

Begin by starting your thread an eye length behind the eye.  Wrap down to the bend of the hook.  Tie in approximately 6-8 fibers of Partridge, about a hook gap length.  (You can also substitute with Pheasant tail or Peacock Sword fibers.)  Next, tie in your gold rib.  You are now going to dub a body of seal or similar Isonychia prepared dubbing.  Begin at the bend of the hook and dub forward leaving enough room behind the eye for your peacock thorax (about an eye’s length & ½ space).  Wrap your rib forward making even spiral wraps.  Tie off your rib and cut off the tag end of it.  Tie in 2-3 stands of peacock herl for your thorax.  Wrap the herl for your thorax.  Approximately 3-4 wraps is all you will need.  Make sure to leave enough space for your hackle.  Next tie in your hackle.  Make 2-3 turns then tie and trim off.  Form a head to the nymph with your tying thread.  Whip finish and trim off your thread.  Finally, apply head cement to the wrapped head.

Tim Flagler of Tight Lines Fly Fishing has an excellent instructional video on how to tie this fly below: 



How to fish this fly – You can fish it as you would any other nymph or you can swing it like a wet fly.  One thing you have to do is to occasionally twitch the fly.  This is a deadly technique on the Catskill streams and it works very well on the Farmington & Housatonic.  You can twitch it with your rod tip or the way I do it, I’ll give it some short fast strips with the line.  As I said earlier, Iso’s are great swimmers darting from rock to rock.  My greatest success has been in the faster water with this fly. 

If you have any questions about this fly or would like to submit a Fly of the Month, I can be reached at 203 305-3850 or pdinice@frontier.com .