Dry Flies and Hatches

Camouflage and camouflage breaking are dominant and defining themes among aquatic creatures, at least during the great bulk of their lives--when they are still aquatic. Among aquatic insects whose life cycle includes one or more final instars as flying adults, water column and stream bottom camouflages are no longer much of a factor. Aquatic insects typically live for only a few days once they leave the their watery environment.

So if camouflage does not play a big role in the dry fly story perhaps accurate, detail-oriented imitation does, at least in the active, ongoing hatch context so many dry fly fishermen seek out and value so greatly.

Snell's Window

Snell's Window is a good starting point. Because of the way light shining down from above is sharply refracted by the shiny flat surface of the water any lens or viewpoint looking up from below, like the eyes of a fish, sees the underside of the surface as a mirror image of what ever is below, all except for a circular viewport directly above the fish's eyes. You can think of this viewport as a cone-shaped window starting as a point at the fish's eyes that radiates upward at approximately 97 degrees. If a fish is resting in the water column looking up, everything above looks like a mirror of the bottom below except for a transparent, circular, unobstructed view of all that is above, approximately the same distance wide as the fish's distance down from the surface.

Vincent Marinaro speculated the tips of a Mayfly's wings would be the first thing a fish sees as a drifting Mayfly first begins to appear at the outside edges of the Snell's Window--above that fish's eyes. Doug Swisher and Carl Richards concurred. From Selective Trout: "As a mayfly dun floats in the current it will be almost invisible until it floats into the (Snell's) Window. The first part of a mayfly that a trout can see clearly is the tips of the wings. We believe that this triggers the first part of the rise."

Perhaps it's a minor point but Marinaro, Swisher and Richards are missing part of the story here.

Long before any Mayfly appears visually in the Snell's Window it or anything else that floats on the surface creates characteristic dimple patterns in the surface mirror above. Others may have mentioned dimple distortions in the mirror but Marinaro and Swisher/Richards missed this issue. The beginning of most rise responces starts long before the fly's visual appearance in the Window. Fish notice those characteristic dimples in the mirror and expectantly position themselves to intercept and gobble what appears to be an arriving morsel. Sometimes a fish might change its mind and "refuse" at the last moment--when the expected food item finally appears in the window. We've all seen that happen a thousand times. But it's important to see last minute refusals as part of a response pattern that started seconds before, when only a telltale dimple in the mirrored surface was drifting above.

I've seen this too many times to count. I have watched brown trout fighting and competing with each other to intercept incoming Pale Morning Duns in 12" inches of water or less, which implies a Snell's Window approximately one foot in diameter. I've seen them dart upstream racing each other trying to get to an incoming mayfly before the other, with their swimming fin race starting from four to six feet away. I've seen rainbows in the Missouri lying in 36" inches of water rise slowly, vertically up to to intercept an incoming mayfly, starting from 12' feet away, far before it was possible for them to see anything in "the window."

Wild actively feeding never-been-caught-before fish seldom refuse anything, real or artificial. Wild fish can be hard to catch but only during dormant hours, of which there are many in a trout's typical day. ^I Fish do learn to be cautious after they've been caught and released a few times. Exactly what triggers those last second refusals is a 64 thousand dollar question. Perhaps the fish noticed an unfamiliar and threatening hook shape hanging down below. Perhaps the fly was dragging across the surface unnaturally because of a tight leader pulling against the current. Perhaps the refused fly was the wrong size shape or color. Now we're getting down to brass tacks.

Exaggerated size and profile anomalies like a bushy #10 Royal Wulff or a Sofa Pillow drifted down to a rising fish in the middle of a #20 Baetis hatch are instantaneous show stoppers. There is little question about that. But now much more like the real thing does a fly have to be? In a later section about spring creek fishing I'll talk at greater length about a "change flies" strategy I learned from the guides I worked with--and who mentored me--at the Yellowstone Angler back in the early 1990s. The key point of the "change flies" technique was not to change to some particular fly or shape, but to change to anything different, of approximately the right size and color, from what just got refused. If a regularly rising fish refuses your Klinkhammer-style Pale Morning Dun switch to a Rene Harrop Cripple or a spent wing pattern or even to a soft hackle wet fly. I spent countless hours watching rising fish on Paradise Valley Montana spring creeks. Regularly rising fish are exposed to a parade of drifting insects in on or near the surface film. Some are drowned and dead. Some rest proudly upright on the surface with wings clasped together so they appear as one. Some have their wings spread apart. Others are still trapped and struggling to emerge from their enclosing nymphal skins. Some have one wing up and the other down. Spring creek and fussy tailwater fish regularly refuse drifting artificials. But almost never refuse anything real. Size does matter, a lot, but I find it hard to believe minor profile details matter much because there is no such thing as a standard profile.

Size does clearly matter, at least in the case of a thick, ongoing mayfly hatch. That was my experience as a fisherman and as a guide, and almost everybody else's too. Has anyone ever argued fly size was not important? Color at this point in the discussion might matter too. Perhaps it does. But if so not nearly as much as size.

How important is color? I'm not really sure. When ever a customer ran out of Pale Morning Dun patterns, on the spring creeks, I put on a Blue Winged Olive and he or she never missed a beat. A March Brown might not be a good Pale Morning Dun substitute but a March Brown is a substantially bigger Mayfly. Too big matters a lot more than too small. When frequent refusals do happen it's clear something seemed wrong to the suspicious fish, but it isn't entirely clear exactly what it is that puts them off.

As a late-in-life birding enthusiast--like my greatly admired friend and currently reigning Dean of all Montana fishing guides George Kelly--I've noticed birds perched on a high branch or a power line are hard to see as much more than a silhouette. If you want to photograph a back-lighted bird you have to over-expose a full three stops at least, and then fight with image editing software to bring a badly over-exposed background into submission. Mayflies and/or Caddis riding in an even more brightly back-lighted Snell's Window would be even harder to see as anything more than a dark, fuzzy, relatively featureless silhouette.

Ray Bergman

From the Sunshine and Shadow of Trout by Ray Bergman: " Under certain circumstances and on clear days trout cannot evaluate either size, color or shape of objects on the surface of the water." And then again one or two sentences later: "Let us hold a a fly directly between the sun and our eye. What happens? Color vanishes, shape is obscured, size becomes an uncertain quantity. "

The Pale Morning Dun Story

Another argument against color as an important determining factor includes the Rocky Mountain States Pale Morning Dun story. If color really mattered the Pale Morning Dun story would need some serious editing.

Most PMD fishermen use small yellow dry flies or emergers. Yellow is interesting because only the male PMDs are yellow and they do leave the habitat almost the instant they hit the surface. ^I Male PMDs wiggle furiously and spin left and right as they drift, but seldom float for more than 12 to 24" inches on the surface before they fly off. After that they're away from the water for the rest of the day. Male PMDs are highly active and they do fly over the water all day long so they're the ones you see. But once airborne they are never in contact with the water again. Not until after mating time anyway. The slightly larger and substantially more lethargic olive colored females are the ones that ride the surface for 20' feet or more. You never see the females after they fly. They go straight to the willow bushes and perch there motionlessly until mating time arrives. Nobody fishes olive PMDs and yet they're the ones the fish are gobbling off the surface. Yes males get eaten too but far fewer because they fly off so quickly. Upright adult males are not there on the surface long enough to get eaten as frequently as the slower moving females.

The Big Picture

As mentioned earlier, if you run out of PMD patterns in the middle of a hatch you can switch to smaller grayer Blue Winged Olive imitations and never miss a beat. Mimicking dry fly color does not hurt your chances, but it is not at all clear how much it helps. Matching the Hatch is important to some degree. But only during a hatch and too big seems to matter a lot more than too small. Royal Wulffs do not work well at all. That is true. But a large variety of shapes colorings and sizes ranging from a bit too big to a bit too small do work. They work well too. It's also worth pointing out small not-weighted soft hackle wet flies can be absolutely deadly during a PMD hatch. As a guide I can't remember a single customer who came wanting or expecting to fish with soft hackle wet flies during a PMD hatch. But I often put them on when it seemed time to change flies. Soft hackle wet flies are a goto fly for me during a hatch, especially so during Fall Baetis.

Fly size and vaguely the right color is easy to get right for any given hatch situation. But real hatches are relatively rare. Most of the time we fishermen have to deal with coaxing reluctant fish fish rather than eager ones. When there is a hatch, and when the fish dimpling all around us are still hard to catch, what is really going on? In the Western USA States there has been a gradual fly design evolution toward mayfly and caddis dry flies that perch closer and more parallel to the water's surface. Rene Harrop no hackle duns, parachute patterns and Sparkle Duns now sell better than traditional high-riding Catskill dressings. The differences are real I think, but small.

Fishermen tend to focus with laser intensity on their drifting flies. Fishing makes it hard to soak in the bigger picture. A spring creek guide has a bit more time on his hands than his clients. In between netting fish and changing flies I couldn't help notice real flies seldom get refused. Real flies do occasionally get refused, but rarely and only on the most heavily and intensely fished waters. I have seen a fish "compound refuse" a real mayfly once or twice, on Nelson's Spring Creek and at Depuy Spring Creek in the Yellowstone River Valley for instance ^I . But for the most part real mayflies get eaten, almost every time. Perhaps the answer is there right in front of us--like the Emperor's new clothes. Real mayflies look a lot like mayflies while our feathery hooks do not. It doesn't take me long to know whether I'm looking at a real mayfly or a hand-tied artificial. Maybe the fish can too, especially so after they've been caught a few times. Perhaps it's it's a minor miracle we ever catch fish at all. Perhaps severe backlighting in the Snell's Window is the only thing keeping us in the dry fly game.

What Matters Most?

So far I've proposed dry fly size is important, during an active hatch, while the roles of color and silhouette matter too but less so. What matters most of all is the fishermen. Call it Chi, Moxey or Aura, what ever it is some fishermen have it in spades and others do not. My lifelong fishing buddy Patrick Jobes has consistently out-fished me for the past 40 years while using some of the fuzziest, ugliest flies known to Western Civilization. It's worth mentioning too that Moxey is not the same as presentation. Casting skills can be learned and refined. The predatory eyes ears instincts and reflexes of the hunter are bequeathed at birth. We have to live with who we are and to make the best of it. You could fish for a hundred years and never catch up to George Anderson. The Universe does have certain fundamental rules that cannot be altered or changed. Moxey is one of them.

None of that discounts the obvious importance of what so many writers refer to as 'presentation.' Practice and skills matter almost as much as Moxey. Years of coaching, long hours of film sessions and on-court experience gradually and inevitably improves basketball players like Jamal Mashburn or Ben Simmons. But it never turns them into Michael Jordon. At playoff time Michael, Magic, Koby, Larry and Akeem matter most of all.

Elaborate, sometimes complex fly tying is fun. Fly tying has been and continues to be a lifelong hobby for me. But I know with great certainty my old friend Patrick will out-fish me the next time we meet on a stream. And Patrick never has much more than a few old time standards in his box, like Gray Hackle Yellow, Parachute Adams, George's Brown Stone, bead head Zug Bug, Latex Caddis and maybe a Yellow Sally or two. And none of them well tied.

With almost equal certainty I feel confident my creative fly collection helps me to keep that disparity in check. If Patrick had access to my fly boxes I would be left even further behind. Cool flies help. A little anyway. The fisherman makes the biggest difference of all.

Notes:

^I Lewis and Clark on the Jeff...they found trout but could not catch