Fly-Fishing: ‘Groob’ proven pattern

A Web site I know of that mon­itors conditions on trout streams in the lower Hudson Valley maintains

A Web site I know of that mon­itors conditions on trout streams in the lower Hudson Valley maintains a running list of fly patterns to have on hand so you can match the hatch.

“Caddis — green, olive, tan and black — in sizes 14 thru 22,” the list begins. “Rusty Spinners sizes 12 thru 22.” On it goes. In all, the most recent update of the list includes 89 patterns.

I don’t have all 89 patterns, but I’ve got flies that are close enough to most of them. And yet, I find myself using fewer patterns all the time. In fact, I have a new favorite that has accounted for many of the fish I’ve caught this year, including most of the good ones, and is starting to make me wonder if I need to carry anything else. It’s a Green Rock Worm, tied in the Czech nymph style.

I began experimenting with Czech (also, and probably more accurately, called European) style nymphing this spring. As a fishing technique and a style of fly construction, Czech nymphing is simply a new take on old things — the “high-stick” style of fishing and simple, grub-style flies that imitate caddis fly larvae.

The Green Rock Worm, which imitates the larval stage of the Ryacophila caddis fly, is fun to tie. I found a video of the great British fly-tier Oliver Edwards making this pattern on YouTube, and try to make mine the same way.

The fly is tied on a curved-shank hook. It has an underbody of sticky-backed lead tape, which helps it sink quickly. The body is made of bright green Antron tri-lobal wool, twisted tightly and wound on with visible gaps between the wraps, giving the fly a distinctly segmented look. Between the wraps goes a shiny under-rib of Krystal Flash. A strip of cellophane covers the fly from tail to head as a shellback, and is held in place by a second rib, this one of medium monofilament, wound deeply into the crevices between the wraps of wool.

I add a small head of dubbed dark brown fur, with a few hairs picked out to suggest the nymph’s legs, but that’s it — no hackle, no tail, no feelers, wings or antennae. The genius of the pattern is its slim profile. It sinks much more quickly than any bead-head pattern.

Pretty much every creek has Ryacophila caddis flies, so trout everywhere are accustomed to seeing and eating them. Even to a trout that has never seen a real Ryacophila, this little bug must look like something good to eat.

In fact, a little pile of them on my kitchen counter, next to the coffee maker, completely grossed out my wife. That’s one mark of a killer fly.

I’ve never used a Green Rock Worm when trout were rising, and probably never will. Surface fishing is just too much fun. If trout are looking up, I’ll work my way through the 89 patterns until I find the one that works or run out of daylight.

But in the absence of hatching fish, the Hare’s Ears, Pheasant Tails, Princes, Zug Bugs and the rest of my nymphs won’t be seeing much action. I’ll reach for the heavy, buggy “groob,” as Oliver Edwards called it, because I know it works.

Categories: Sports

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