In winter, fly fishers, reminisce about seasons past, dream of seasons to come, and tie flies. Impressive creations emerge and some even achieve brief notoriety. Rarely indeed does one work out well enough to be listed in a pattern dictionary or deserve to.

What makes a fishing fly a classic? Some like the Coachman, Grizzly King, Silver Doctor, Professor, Brown Hackle, and Soldier Palmer have been around for hundreds of years. Angling historians believe the latter is the fly Aelian described that Macedonians were using to catch trout some two thousand years ago.

A few modern patterns like the adams, Mickey Finn, and Muddler Minnow have proved themselves and seem also to be destined for immortality.

Although vastly dissimilar, there are four qualities the above flies share.

First of all, they are simple. Many effective patterns haven't survived because they were too time-consuming to build. Commercial tiers couldn't afford to make them.

Secondly, they are made from easily obtained materials. Patterns that depend for effectiveness on exotic or rare components enjoy limited popularity.

Third, they are durable. One that will take a fish or two before starting to disintegrate is an abomination.

Fourth, and most important of all, they must consistently produce well. A good fly is like a caricature or an impressionist painting. At first glance, it will make a fish think, "I know what that thing is; it's edible".

For instance, even a good photograph might have to be examined closely to identify the person pictured, but an artist's caricature that exaggerates one or two features of the same individual can immediately make you think, "Why, that's so-and-so. I would know him anywhere".

A fly works the same way. Often exact imitations are not as effective as impressionist ones that over emphasize one or more details. With the latter, a single, quick look is often enough to trigger a fish's feeding instinct.

An artificial intended to represent a specific natural should emphasize some characteristic of that organism. For instance, fresh water shrimp have prominent black eyes so a shrimp pattern tied with a shiny black head is usually more productive than one that isn't.

Many successful flies suggest more than one order of aquatic life. A new pattern developed by R. E. "Bob" Turner of Evansville, Wisconsin is one of these.

A simple concoction, with a gray squirrel tail hair covert over a silver body and grizzly hackle, it meets the foregoing criteria and then some.

It could be taken for a smalI crustacean, a winged insect swimming under water to deposit eggs, a stone fly, a may fly, or dragon fly nymph, even a baby mouse or navigator shrew. It would be hard to find a midwestern lake or stream where the fish wouldn't associate it with something they are accustomed to eating.

Here is how Turner's new fly is tied:

First coat the hook shank with fly head cement. Then secure the tying thread near the eye and spiral it back along the hook shank to the bend and half-hitch it. Cement this winding.

Make all winds in the same direction around the hook. Be sure to cement every half-hitch and don't use waxed thread. Cement won't penetrate wax. Use clear lacquer cement.

Next tie a clump of gray squirrel tail hair on the hook with the white tips extending rearward like a tail. Do this by making a couple of turns around the hook and hair where the thread is already half-hitched and half-hitch again. Next fold the rest of the squirrel hair over so it extends back of the hook also. Make two or three winds of thread over this and the hook. Half-hitch, then make another half-hitch just ahead of it around the hook shank. This is where the ribbing material wilI be tied on.

Secure one end of a two-inch piece of oval silver tinsel here with another thread wrap and half-hitch and advance the thread to a spot two-thirds of the way to the hook eye and half-hitch again.

Tie one end of a four-inch strip of flat silver tinsel at this place and form a body by winding it back to where the hair is secured, then ahead again to where it is tied on. Fasten with a thread wrap and a half-hitch.

Rib the body by spiraling the oval tinsel ahead to the same place and tying off. Coat the body and ribbing with cement.

Trim the soft fibers from the base of a grizzly hackle feather and tie it by the butt at the very front of the body. Wind this on edge around the hook for two or three wraps. Try to make each turn on top of the previous one or, at least, very close to it. Tie down the last wrap with several turns of thread, half-hitch and cement. Pick out any fibers that were tied down.

The reason for making extra thread winds here is to provide a base for the front of the covert (or shelI back). Trying to tie material to bare metal is a lost cause.

Next hold a toothpick crossways on top of the hook and fold the squirrel hair forward over it. Keep the toothpick towards the rear of the body. Try to hold it square and level. This will help form a neat covert.

Make several turns of thread around the hair and hook, then remove the toothpick. Half-hitch the thread and cut off the excess hair so it slopes from knot to hook eye. Saturate the knot and hair butts with cement.

Cover this by building a neat head with tying thread. Finish with a whip knot and give the head a coat of cement.

You have just tied a "Turner's Shellback" a low-key pattern that at first glance, probably doesn't impress anybody much except fish. It is also one of the best all around wet flies I have fished in a long time.

In the few weeks I have used it, it has been a dependable producer on both lakes and streams. I have taken bluegills, bass, crappies, perch, and some small walleyes with it. On at least two occasions, it has turned what started out as fishless days into successful trips.