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Mercer's Missing Link

Mercer's Missing Link

Missing Link: That fly pattern which links together common features of many different insects, and insect life cycles, making it appear a safe and attractive meal to fish in nearly any surface-feeding situation.


Have you ever watched as a trout 20 feet away rises with seeming reckless abandon, but momentarily vanishes each time your fly passes over its feeding station? Do you remember the feelings of personal inadequacy as this creature with a brain the size of a #16 Parachute Adams steadfastly rejects the next half dozen patterns you show it using perfectly timed, drag-free drifts? It's these experiences that either crush, or feed the resolve of creative fly tiers.


A Fly is Born


The Lower Sacramento River was in rare form. All day long we'd been nymphing up 16- to 20-inch wild rainbows from her wide riffles and endless current seams, sweating like Arizona roofers in the 105-degree July heat. Then, as the sun dipped low on the mountainous horizon, fish began to porpoise on the surface, inhaling dry caddis, and prompting a familiar twinge of apprehension. For the three decades I've thrown caddis drys at these summertime risers, my success rate has been wildly erratic, causing my confidence level to follow suit. This twilight surface feeding spree is fairly dependablethere are almost always reaches of the river where the big trout come up for the last hour of light. Finding trout to throw to has rarely been a problem. But unlike other fisheriesincluding some pretty darned technical onesthe Lower Sac had always toyed with me. One night I'd land half a dozen big rainbows and be on top of the world, certain I had finally solved the dry-fly mystery; two nights later, same number of fish working, same pattern, and I couldn't touch a fish. What was the deal?


One night, following a particularly memorable beating from these fish, I sat down to create a "new" dry. I badly wanted to think outside of the box in its design, not limiting myself to traditional fly-tying thought processes. Though there is a lot of good to be found in the ideas of those who have come before, safely staying in those confines can also significantly reduce the potential for discovery.


It occurred to me the one life stage of caddis I'd rarely even considered had nothing to do with a nuance of emergence, but was instead at the reverse end of the cyclea dead or dying insect. I presumed the body needed to emulate a "wasted" natural's abdomenwispy, yet with a touch of sparkle for what little trapped air might still remain. And I wanted an abdomen that hung down in the surface film, appearing drowned, rather than floating high and dry on top.


The view of Mercer's Missing Link, as seen from below. (Ted Fauceglia photo)


Rejecting a conventionally dubbed body as being too meaty, I recalled a friend who ties many of his mayfly drys with simple thread bodies. Why wouldn't it work here? Yet that didn't address the subtle flash I desired, so stealing an idea from my Poxyback series of nymphs, I ribbed the thread body with a strand of Flashabou. Wanting to create an illusion of depth, in a desiccated but still tasty abdomen, I coated the thread with a film of Softex, which also served to guard the frail rib against trout teeth.


Realizing dying caddis often appear splayed on (and in) the water's surface, I felt a downwing profile could be key. This was something I'd rarely seen incorporated in caddis patterns, though from "retired" specimens I'd collected, I sensed the potential to elicit a strike trigger here was considerable. I wanted these drowned wings to resemble the naturalsextremely frail and somewhat translucent, not opaque or with a defined profile. They were supposed to look haphazard and . . . dead.


I chose Z-Lon yarn, and tied each sparse wing in front of, and tight against a dubbing bump to make sure the yarn fibers didn't simply collapse against the hook shank when wet.

The idea was for them to appear swept back, but still recognizable as two separate entities.


Knowing that trout often fixate on drowned adults (of all insect types), I preened these wings downward, slightly below the axis of the hook, wanting them to be just below the water's surface.


Finally, wanting a low-riding profile as well as a visible back-wing silhouette, I borrowed Ralph Cutter's ingenious idea from his E/C Caddis, and parachute-hackled an elk-hair wing. I inspected the finished product in my visefrankly without a lot of enthusiasm, due to its sparse, unremarkable appearanceand tossed it into my box, certain it would never find its way to the end of my leader. It just didn't have "the look."


This underwater view of a Sulphur Dun emerging from its nymphal shuck shows what a trout sees from below, but the trout might interpret this information differently than we imagine. (Ted Fauceglia photo)


The next evening on the river I started with my standard favorites, but to little availthe fish were rising everywhere, but not to what I was offering. More out of resignation than hope, I finally reached in and plucked what I called the Cadaver Caddis from the box, and knotted it on. First cast"slurp"and a hookup. My friend watched mutely from upstream, slightly surprised.


Convinced it was a fluke, I dried the bug on my shirt, picked a new target, and cast again. Slurpand I came tight again! Now my heart rate started to elevate slightly, and I noticed my fishing partner begin to edge slowly down toward me. Still not convinced (30 years, remember), I threw to yet another rise 20 feet from my rod tip, and it happened againthree fish in as many casts! I went on to hook many fish in one magical hour that night, and missed several other takes, eliciting strikes from every single trout I cast to. Unbelievable.


Even more astounding, the fly continued to produce at this torrid pace for the rest of the summer. Evening after evening, my confidence soared as I knew I had a good chance of hooking nearly every trout I put a good cast on. It was like a dream.


That autumn, another friend and I found ourselves in the Rockies, plying the demanding flows of the Firehole River. Each cloudy afternoon flotillas of Baetis drifted down the gentle flats of Biscuit Basin, with the greedy mouths of rainbows and browns interrupting their journey.


It was exceptionally demanding, with fish immediately going down at the merest hint of drag, or anything else out of the ordinary. We felt fortunate to take one fish out of each pod before they wised up, and we'd have to go in search of more fish. Just on a lark, as the trout were confidently sucking in the tiny mayflies (but completely ignoring my imitations), I took off my #22 parachute and tied on my new Cadaver Caddis. Don't ask why, it was one of those strange decisions based on very little coherent thought.


I proceeded not only to catch a fish on the far-too-large #16 dry, I hooked all eight fish in the pod. Could this truly be a magic fly? I moved down to the next group of risers, and quickly stuck over half of them. I then realized that this pattern had something that attracted fish even in situations I never would have imagined.


Years later, this pattern is almost always my first choice when fishing a dry flywhether for selective trout fixated on a particular mayfly or caddis, or simply covering water as a searching pattern. There is clearly something about it that inspires confidence that it is a safe and easy meal.


As a creative tier, I want to understand this phenomenon. Why would a heavily pressured trout feeding exclusively on tiny mayflies suddenly and gullibly agree to take a much larger fraud, one which to my eyes wouldn't seem to even remotely resemble the existing naturals?


An underwater view of a spent adult caddis, with its wings outstretched on the water. (Ted Fauceglia photo)


It's my experience that much has been considered about the intellectual process of creative tyingusing focused and purposeful imagination in design and material selection to imitate various fish foodyet the intuitive part of the design process remains largely ignored. Why did I decide on this particular combination of materials for the fly I eventually renamed the Missing Link? I couldn't continue calling it a caddis, as it worked too well over a broad range of situations.


Why has this pattern proven to be so irresistible to fish, while seeming a bit straggly and unimpressive to my eyes? The truth is, understanding how fish seeboth natural prey and our emulationsis an imperfect science. Our eyes are created differently than theirs, for different purposes, and so we are forced to make certain assumptions when designing imitations of their food that may or may not translate accurately. This can be frustrating when seemingly perfect emulations elicit only refusals. Magic happens when some (often) unintended combination of materials proves deadly effective.


If I'm honest, when I was trying to mimic trapped air bubbles on the drowned abdomen of the Missing Link, was a Flashabou rib the first thing that sprang to my mind? No. Not even close. My mind immediately went to the need for a spiky, slightly flashy dubbing. Makes sense, right? A dying caddis has some small hairs on its body, some of which will likely still trap tiny air pockets. Yet part of me struggled with the bulk dubbing would create, and before I could even reason through this, my mind took an immediate, on-its-own jump to my friend's thread-bodied drys. Something else intuited I still needed flash, and out of nowhere my fondness for Flashabou-ribbed nymphs drifted into my mind. And when my lagging, one-dimensional, controlling thought processes finally caught up, the work had already been done. All I had to do was coat some goop on, and apparently I'd created something fish really like.


Some might call that process intuition. And as is so often the case in such matters, I didn't immediately appreciate my own creation. Sure, the fly immediately worked exactly as I'd hoped, yet I pulled out the pattern only when I felt fish were keying on dead and dying caddis. It might have languished in ignominy as a limited-use specialty fly. Instead, it turned out to be the single most effective dry fly I have ever used.


I could ramble on about the importance of this same process of intuition in devising other parts of the Missing Linkand about how this fly must imitate what fish often see from belowbut as creative tiers, I think we would do well to keep an open mind. Fish see differently than we do, and it's not always possible to logically put ourselves in their shoes. Your gut instincts can also play a powerful role in the creative process.


Not all materials are best used as advertised. And as we sit down to create something new, it can be useful to let our imaginations wander and relax a bit, meandering outside of the strict and rigid lines of what we think is true. Be willing to fail occasionally, knowing that this is sometimes necessary if we hope to discover just exactly what it is that fish really want.


Mercer's Missing Link



Hook: #12-18 Tiemco 102Y.


Thread: Camel 8/0 UNI-Thread.


Abdomen: Thread ribbed with pearl Flashabou, coated with Loon UV Flow.


Thorax/Wing Splitter: Small clump of UV brown Ice Dub.


DownWings: Dark dun Z-Lon.


UpWing: Elk body hair.


Hackle: Dark dun saddle hackle, tied parachute.


Mike Mercer is Fly Fisherman's West Coast field editor, and the author of Creative Fly Tying (Wild River Press, 2006). He has been a travel associate at The Fly Shop ( at Redding, California for more than 25 years.


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