December 05, 2022
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This article originally appeared in the September 1983 issue of Fly Fisherman magazine. Click here for a PDF of the print version of "Diptera: The Fly for All Seasons."
What follows here is some practical information about fishing flies to represent Diptera, those wee two-winged insects found balling up by the trillions year-round along trout streams from coast to coast. Excluded is the entomology of Diptera, which is so complex that I gave up trying to fathom it long ago, at the loss of not a single fish. In fact, I’d been fishing Diptera imitations, simply calling them midges, for a long, long time before I was even aware they’d gotten the going-over from anglers determined to dabble in science. Blissfully I fished then and continue to do so now, knowing little more about their body segments or wing veins than I did the day I discovered that trout like to eat them.
For clarity, I will say that the tiny bugs of the Diptera family, including mosquitos, craneflies, and a host of midges (gnats, no-seeums, black flies, snow flies, and on and on) all have a common Latin derivation: di, meaning two, and ptera, meaning winged. Unlike mayflies, caddis, or stoneflies, Diptera have no secondary set of wings. But, then, the Diptera that interest me most as an angler are so small that secondary wings are hard to spot anyway.
Many anglers don’t like to fish midges. They view flies smaller than #18 with a disdain akin to that I have for the de-romanticizing of fly fishing with too much science and its wicked step-sister, verification. Nonetheless, fishing experience at home and abroad has afforded me some insights into fishing midges, worthy of all but perhaps the ultimate purist and the incurable romantic.
First: Diptera constitute a kind of common denominator among the world’s trout fisheries. I’ve never struck a trout stream where I didn’t find these insects, usually in abundance. For example, while scouting for fins in the Middle Atlas Mountains of Morocco recently, I discovered a lovely spring creek where plump browns were sipping emerging Diptera, just as browns sip Diptera on the Letort of Pennsylvania, Nelson’s Spring Creek of Montana, and the Test, Itchen and Avon of Great Britain. Similarly, clouds of Diptera shade feeding trout on the Beaverkill, Delaware, the Madison, the Big Horn, eastern and western American rivers, and on the Risle of Normandy, the Elle of Brittany, both in France, and Laxa Laxadalur, the magnificent river of northern Iceland where they represent the staple of the brown trout diet. Thus, it is fair to suppose that when encountering an unfamiliar trout fishery the angler shouldn’t go entirely wrong when he’s carrying Diptera imitations and knows how to fish them.
Second: Diptera tend to abound along trout streams, at least the streams I know best, for longer sustained periods each year than all other aquatic insects. Fishing the Beaverkill near my home, for example, I’ve taken trout on the surface or in the surface film using Diptera imitations during every month of the year. And these small flies have proven notably effective in the late fall, winter and earl spring when the only viable alternative is to fish down, dirty and slow. According to my stream notes, I hooked 32 trout on March 19, 1982, for instance, 29 on a surface midge and but three while probing the bottom with a small dark stonefly nymph. Reliability, then, would seem to demand that attention be paid to Diptera's potential.
Third: The largest trout of many waters–including fish you'd expect to take perhaps only on streamers–rise readily during Diptera emergences. Time and time again, I’ve witnessed and sometimes caught trout on midges (#22 to #28) fished on top, particularly along flat stretches, after failing to lure the fish to conventional dries and emergers representing the prevailing hatches. The key to understanding why a trout of apparent cannibal size might shun, say, Hendricksons while feeding freely on minutae probably derives from the sheer numbers of Diptera frequently available to the fish at given times. True to its opportunistic nature, a big trout can leave just beneath the surface for protracted periods, expending no more energy than is required to tip its head up and down while ingesting its fill of tiny insects. Paradoxical though it may seem, therefore, my experience teaches that I stand a better chance of hooking big trout when fishing midges than when using more typical dry flies, except perhaps when the conventional dressings imitate the very largest of aquatic insect species, such as the eastern green drake that shows for no longer than three weeks each season.
A typical angler prejudice against fishing midges issues from a sense of insecurity born of the inability to see his fly on the water. Why some anglers confidently fish nymphs upstream while distrusting midges, I'm not certain, but the root of this prejudice represents the perfect starting point from which to discuss techniques that enhance Diptera fishing.
To the angler, the most important stage of the life-cycle of a typical Diptera (i.e., the egg, larva, pupa, and adult) is the pupal stage. Even fished in the surface, a pupal imitation that represents a helpless insect struggling in the film to free itself from its shuck prior to flight, has proven considerably more effective than a dry midge that floats high on the water. However, the dries you do opt to fish from time to time will likely be so small (my favorite is nothing more than clipped hackle wound on a short-shank #26 or #28 hook) that the best pair of eyes seldom will see them on the surface, except when fishing the shortest of lines. The kicker, then, isn't to be able to see your fly at all, any more than it is to be able to see a nymph as it deaddrifts downstream toward you under water. Instead, the trick is to know precisely where the fly is at all times, so that when a trout rises for it, you are prepared to set the hook. Certainly it requires considerable practice to develop this skill, but with time, most anglers can learn to monitor fly drift without actually seeing their flies, to sense the speed and direction of drift by relating stream velocity and bearing of current to the ability to put their flies exactly where they want them. With no arrogance intended, I respectfully suggest that an angler's time is much more productively given to mastering this skill than to mastering complex data attenant to Diptera entomology.
Through the years, I've had minimal success trying to fish Diptera larvae or pupae imitations deep. This does not imply that trout don't feed on these midges near the bottom, but rather serves to illustrate that trout are reticent to move far up, down or to the left or right to take tiny insects. Thus, unless you've spotted a fish feeding in deep water and are able to put a Diptera imitation on its nose, you are, in effect, relegating fly presentation entirely to chance, like trying to sink a long birdie putt while wearing a blindfold. No, midges are not the flies for prospecting.
Happily, Diptera imitations are best fished to rising trout whose feeding rhythms you've carefully monitored in advance. Wiring the feeding rhythm is essential, because the typical abundance of the natural insects dictates that you insure that your target fish spots your offering among the multitudes. To accomplish this you must time your presentation so your fly passes over the trout's feeding station at precisely the instant the fish is prepared to sip a natural. Ideally, then, by means of meticulous timing, your fly must be the only fly the target trout sees as the fish opens its mouth to take.
To show your fly correctly to the rising fish requires that you be positioned to get an absolutely drag-free drift. Although your midge pattern may be no more than a wisp of dubbed fur on a #28 hook, if it drags the trout usually will reject it and the trout will likely spook. Your task is facilitated by planting yourself across and somewhat downstream of your target trout, then three-quartering the fly upstream, casting either a right or left curve into your line and leader, depending on whether the stream flows from right to left or left to right.
Long fine leader tippets are generally essential to Diptera fishing, because (1) typical Diptera water is flat and clear, (2) heavy tippets will just not pass through the hook eyes of such tiny flies, and (3) a fine tippet enhances the impression of a free-floating insect to most trout. Frequently, I opt for eight feet of 7X or 8X tippet material, which, ironically, makes presenting the midge a more manageable challenge than trying to do so while using conventional tippet lengths of two or three feet.
When presenting the midge, try dropping your casting hand to your waist immediately in the wake of your powerstroke, while maintaining the rod tip pitch high over the water. This casting technique will cause your leader tippet to tumble and bunch up ahead of your target trout’s feeding station. The current, then, will catch your midge and carry it downstream toward the feeding fish as the coils and S's in your tippet slowly straighten out behind the fly.
The trick, of course, is to ascertain your fly's probable line of drift before initiating each presentation. This is made easier, incidentally, when you discover that Dipterafeeders seldom need be led by more than a foot. My rule is to lead a trout not one inch more than I perceive as essential to get the job done.
Despite contrary claims, fishing Diptera imitations requires no special equipment. In competent hands the same rod with which you'd fish a standard #14 dry and 5X tippet will handle light tippets and tiny flies nicely with a light (but not tentative) touch. When choosing a rod specifically for midging, however, consider perhaps a nine-footer for 5-weight line on big waters; and eight- to eight-and-a-half-footer for 5-weight line on mid-size streams, or a seven-and-a-half to eight-footer for 4- to 5-weight line on small waters or extreme low water conditions.
Effective Diptera imitations run the gamut from #20 through #28 and in colors from black to cream. Among wets, I like a simple pattern tied with a stripped peacock-quill body and a bit of fur dubbed as a collar. The dry I use most often is an emerging pupal pattern developed by Mike Kimball of Ithaca, New York, unquestionably among the world's most skilled midge fishermen.
Diptera fishing is generally associated with the sipping rise on flat water, especially spring creeks, limestoners and chalk streams. However, most surface water streams also abound in Diptera species largely ignored by the majority of anglers. When you see trout sipping on a flat stretch along your favorite stream, odds are excellent they are working on Diptera.
Lastly, there's the ultimate challenge: fishing Diptera in or on fast water. Although not widely perceived, some prolific Diptera hatches occur on pocket water, riffs and even the most turbulent of rapids. That dusting of miniscule bugs you observed over the river last season were probably one Diptera species or another, and those trout you were so proud to have spotted sipping amid all that turbulence were probably filling up on Diptera pupae.
Next time, why not test yourself. Put away the standard wets or dries, add a long, fine tippet, cinch on a #28 pupa and find out how good you really are. The fish may give you fits at first. But, ultimately, you're going to be glad you allowed yourself to go a little bit "Dippy."
Kimball's Diptera Emerger
As simple as the pattern appears, hundreds, perhaps thousands, of hours of Mike Kimball's matchless skill and expertise went into the research and development of his Diptera emerging pupa, shown in the accompanying photograph, as dressed by Galen Mercer. This pattern has proven itself uniformly and remarkably effective on rivers and streams across America, as well as abroad. It is, by the way, the fly with which Mike created quite a stir when he was observed solving the apparent enigma of those evening rises on Armstrong's Spring Creek in Paradise Valley of Montana.
Here's how it's tied:
- HOOK: #20-#28, Mustad 94833 (TDE, 3X fine).
- HEAD: Black, brown or cream midge thread, depending on the body shade chosen.
- TAIL: Several fibers of teal flank feather, tied long and splayed co represent the pupa's body shuck trailing behind it prior co falling away.
- ABDOMEN: None.
- THORAX: Dubbed fur or poly in black, brown, rusty brown, olive, pale yellow or cream.
- WING CASE: A small section of white or light gray poly yarn, tied in so there's an exaggerated hump at the rear of the case and a gradual slope toward the eye of the hook.
Art Lee, FFM’s Eastern field editor, is author of Dry Flies for Trout on Rivers and Streams, published by Antheneum Publishers.