Now that winter has brought a little time for fly tying, why not make some nymphs to try next season.

"Nymph" is a term entomologists use for the immature stage of insects that do not undergo complete metamorphosis between juvenile and adult phases. Among fly fishers it has been used loosely enough so it has come to mean aquatic larvae, pupae and even crustaceans such as fresh water shrimp and sowbugs, also.

Many fly anglers stick pretty much to floating lures and limit their sub-surface ventures to occasional streamer fishing when the water is high and roily.

It is fun to see fish rise to a floating fly or popper and difficult not to recognize a take on the surface or mistake the positive tug of a hit on a streamer for a drifting twig or weed.

Strikes on nymphs are often gentle enough to be almost undetectable. It takes experience and concentration to consistently take fish with these imitations. Why use them? They bring an angler many, many more chances at fish than the other types of flies will and larger ones to boot.

Ichthyologists tell us that more than seventy-five percent of an average trout's diet consists of underwater organisms such as nymphs, larvae and small crustaceans and the same is true of many other game fish. The trick to using them is learning to sense when your nymph is being mouthed and reacting quickly enough.

I taught a fly tying course for years. It ran from the first week in January until the first week in May. For the final lesson we would meet on the shore of a pond or lake and make sure everyone's outfit was matched correctly and he or she would cast well with it.

I recall one of these sessions when a student was trying to take bluegills on a nymph. Everyone else was having a least moderate success, but this fellow was fishless. He was making nice long casts and retrieving at the same speed as the fishers on each side of him, but with no luck.

Finally he started counting to ten, then lifting his rod tip. About half the time he would hook a fish. Think how many he would have caught if he had been able to recognize when the fly was being taken.

Incidentally, using nymphs for panfish is excellent practice. Watch the line near the leader very closely. At the slightest draw, deviation, pause or anything else that isn't quite normal, pull! After awhile, you will find yourself setting the hook and finding fish on, and if somebody should ask, "How did you know to pull then?, you really won't be able to explain. It will be as though you have acquired an extra sense.

When I started nymph fishing years ago, I tied and used a pattern that, for lack of a better name, we called peacock herl nymph. Later I learned it is very similar to the lead wing coachman nymph.

Here is how it is made: Secure a 1x or 2x long hook in the vise. Twelve is a good size. Coat the shank with fly head cement, wrap tying thread from eye to bend, half-hitch at the rear of the winding and coat this with cement also.

Tie a clump of brown hackle on for a tail with a couple of thread wraps and half-hitch where the previous half-hitch was made. Put a drop of cement on the knot. Use ten or twelve fibers and let them extend beyond the hook about two-thirds of the shank length.

Secure a short piece of fine, flat gold tinsel and three or four strands of cock herl to the hook in the same place and same way the tail is fastened, tie the tinsel on first and be sure the herl is tied on by its tips.

Now advance the tying thread to a place half-way between hook point and eye(usually about two-thirds the shank length) and secure with a half-hitch, tie in a section of goose or duck flight quill about one-quarter inch wide here leave it stand for the time being. Half-hitch the thread and let it hang.

Wind the peacock herl ahead to where the quill section is secured. Tie in and half-hitch, but don't cut off the excess herl. The herl should be all wound at once, as if it were a single strand. Spiral the tinsel ahead for ribbing (about three turns is fine). Tie this off, half-hitch, cement and cut off the excess tinsel.

Now wind the rest of the herl ahead of the upright quill piece to make a roundish clump a little larger diameter than the abdomen and tie it off far enough back of the hook eye to allow room for hackle and the fly head. Now, cut off the excess herl.

Tie on a brown feather for shoulder hackle, make two or three wraps with it, tie off, cement the knot, trim and discard the excess. Lay the quill section forward over thorax and hackle to imitate a wing-pack tie down, trim and make a head with several turns of thread, a half-hitch and a whip-finish, cut thread and your nymph is completed.

Holding a toothpick at right angles to the hook and folding the quill section over this will help make a nice, even, natural looking wing cover. Slide the toothpick out after the front is secured.

As May fly nymphs get closer to changing into adult insects, their wing covers become progressively darker. Since these are the ones most likely to be available to fish, very dark gray and even black quill sections are probably best for wing covers.

In this case, peacock herl is an exceptionally well-suited body material, not only because it has iridescent reflective qualities but also, its texture is suggestive of nymph gills. Most immature aquatic insects breath through appendages along the abdomen or thorax and the fibers projecting from wound herl simulate this nicely.

The procedure described above is the basic technique for all nymph construction. As a rule, other patterns differ only in material used.

Coachman nymphs and many others are constructed without tinsel, but I am a firm believer in tinsel ribbing. Most living nymphs are, at least, semitranslucent at the joints between abdominal segments and some are actually transparent. Tinsel, by reflecting its surroundings, simulate these translucent bands very convincingly.

I had opportunities to test them both in water clear enough so fish could be observed and found that tinsel-ribbed ones were taken much more readily than those without.

A living nymph's thorax and wing case are opaque so tinsel would serve no purpose there.

The nymph described is probably the best all-around one I know of, so make several in various sizes.

I use other patterns of course. Some I rely on heavily at certain times and certain streams, but the peacock one is the most nearly universal. It does a good job in most streams and an excellent one in lakes.

It took the largest brook trout from a Northern Wisconsin lake that I ever caught. In sizes ten and eight, it has been a very good producer in brown trout streams.

Fish it deep and slowly. The big brook trout I mentioned picked up one off the bottom that was lying motionless almost at my feet. I had retrieved and was winding up line preparatory to moving when the fish took. Another time a large bass took one almost the same way, except that I had dropped the nymph into the water where it sank to the bottom while stripping off line for the first cast. The bass picked it up while it was lying there.

They produce well if fished slowly over relatively shallow, dark, mucky bottoms; areas we think of as dragonfly nymph or hellgrammite habitat.