When you look at flies from a first-principle perspective, you’ll notice they are based on two fundamental elements: the fly and the hook. The fly, in its myriad forms, attracts the fish, and the hook catches it. In the vast majority of cases, these two components are permanently combined into a single unit, which we call a “fly,” even if it is really supposed to represent a leech, crayfish, or squid. Take a look in most fly boxes, and you’ll notice this is the way 99 percent of flies are made. But not all of them.
Minnie’s Tubes
In 1945, a Scottish fly tyer by the name of Minnie Morawski departed from fly-tying orthodoxy when she developed the tube fly. Minnie’s fly solved two problems. Salmon can have an irritating habit of nipping at flies, but not getting hooked. By placing the hook at the very back of the fly, Minnie’s design helped turn more short strikes into landed fish. In addition, once the fish was hooked, the fly would slide up the tippet, reducing the chances that it would be destroyed by sharp teeth. Seventy-five years later, tube flies aren’t confined to Atlantic salmon fishing. Minnie’s tubes have caught everything from steelhead to sailfish.
The tube fly, like the wheel, is a relatively simple idea that seems so obvious in hindsight. Perhaps it is this simplicity that led Minnie’s name to fade into obscurity while other flies have made some anglers almost household names. Or maybe it’s just the passage of time. Seventy-five years is a long stretch, especially in a world where innovation happens at an almost exponential pace. Whatever the reason(s), I think Minnie was one of fly fishing’s greatest thinkers.
Speed and Angst
Regular readers may recall that in the May/June 2019 “Gearhead” column, I outlined a modular fly concept that took a somewhat different approach to separating the fly from the hook. That design is based on the bass angler’s worm hook. The fly itself is tied on a piece of 2-millimeter silicone tubing, which can be quickly and easily slid onto or off the hook. A small chin under the hook eye, originally designed to lock a plastic worm in place, keeps the fly firmly in place, too. Since there’s no need to tie a new knot, changing modular flies takes just a few seconds. If the hook point gets dinged up, all you do is replace the hook and reuse the fly. Like Minnie’s tubes, a modular fly can last longer than the hook, which is helpful when you are fishing complicated patterns that require more than a few minutes in the vise.
While the modular fly is a good match for many fly-fishing adventures, it has one major limitation — it doesn’t work with small flies. Even the smallest worm hook is too big for most mayfly, caddis, or midge patterns. Having gotten used to the efficiency of the modular design, I found this lack of scalability annoying.
During a tough day on a lake, I’ll go through a bunch of flies, a lot of knots, and usually a length or two of fresh tippet. Despite the fact the previous “Gearhead” explored knots, I am not that fond of tying them. Big fish can break knots with alarming ease. To avoid this wretched outcome, I redo a knot at the merest suggestion it’s not right. Seeking relief from knot angst drove me to think about ways to make smaller modular flies.
Bassin’ Breakthrough
Ironically, the solution came while fishing big flies for largemouth bass. A number of chunky bass had corralled schools of fat shiners into a couple of shallow coves at a nearby lake. This lake gets a lot of pressure, and its bass can be difficult to fool. They’ve learned to avoid many of the conventional angler’s lures, and that was certainly the case with the shiner bite. The only folks who were consistently catching f ish were those who were fishing with actual shiners.
Undaunted, I lined up next to the bait guys and started casting a rather obese anchovy tube fly that seemed like a reasonable facsimile of a shiner. To keep things exciting, every few minutes, the water would explode as another shiner became a bass breakfast. It didn’t take too long to get the first grab. The fly had just passed a patch of tules when everything went solid. Unfortunately, the grab did not become a hookup. A few minutes later, another bass hit the fly, and just like before, was off before it was on. This happened three more times before my rod finally bent over. The guys fishing shiners erupted into a loud cheer as a three-pound bass came to hand. I got one more grab before the morning fog burned off and the bass stopped binging.
The feeble grab-to-hookup ratio suggested the chubby ’chovy tube fly had a design problem. Perhaps the bass were hitting the front of the fly, well away from the rear-mounted hook. The fly’s rotund profile partially shielded the hook, further complicating matters. It seemed like a fly with a fully exposed hook located in front of the fly might do the trick. Coincidentally, this was how the bait guys had rigged their shiners.
I’d previously tried this approach in the surf with tube flies tied on sections of silicone tube. Instead of running the tippet through the tube, a bare hook was tied onto the tippet, and its point was speared through the tubing. Unfortunately, the tubing was a bit weak, and the fly would inevitably tear off after a half an hour of hard casting. Something more robust was needed.
Fly Baiting
Scanning my fly-tying bench, I spotted some jewelry designer silicone stretch cord that I originally purchased to make transparent ribbing on midge pupae. The stuff is very strong and very stretchy. I wondered if it might make an elastic eye into which you could slip a bare hook. I tried to explain this concept to my friend David. After a couple of attempts, he got it. His response was, “So you’d bait a bare hook with your fly.” Exactly.
It took a few tries to work out the bugs, but eventually, the stars aligned. The solution was ridiculously simple. I inserted a short section of straightened paper clip into the fly-tying vise and looped and tied a one-inch piece of silicone cord onto the end of the paper clip wire, forming a small, stretchy eye. I slid an appropriately sized hook into the silicone eye and pulled the cord tight, creating a snug-fitting eye. A few tight wraps of thread and a drop of superglue locked the silicone into place. I then tied the rest of the fly onto the paperclip in the same manner you’d use with a regular hook.
Back at the lake, the fly was a success. Most of the grabs turned into hookups, including one bass that was clearly over five pounds. As I gently released that fish, one of the bait guys turned to me and said, “On a fly, that’s so cool.” It sure was.
Now that the concept had worked on large baitfish patterns, it was time to see if it could be radically downsized. I replaced the paperclip with 22-gauge copper wire onto which I lashed an eye made from the smallest-diameter silicone cord, 0.5 millimeters. Once the superglue had dried, a slip of pheasant tail quickly produced a good-looking Pheasant Tail Nymph.
Over the next couple of hours, a succession of nymphs, dries, soft hackles, and emergers came out of the vise. By replacing the wire with monofilament from the butt end of an old leader, it was possible to make almost weightless dry flies with beautifully translucent bodies. Replacing it with lead-free wire and beads produced nymphs that sank fast. Further experiments with pieces of fly line and twisted silicon cord created some great-looking dry and stuck-in-the-shuck emerger patterns. I decided to call these “slip-on flies,” since that’s their defining feature.
Umwelt
There is one “problem” with the slipon design that most folks will notice right away — having a bare hook hanging off the front of the fly seems totally wrong. It doesn’t look like a fly, and instinctively, we know the fish will reject it. This is where things get interesting.
When it comes to fly design, it’s important to understand that sensory perception (sight, touch, and so on) is species specific. As such, the world humans perceive is likely radically different from the world fish perceive. This theory of the Umwelt (German; translated as meaning “the world as it is experienced by a particular organism”) was originally described by the German biologist Jakob von Uexküll in 1934.
I first became aware of Umwelt as a child. Back when kids were still allowed to have an unsupervised life, I’d head off to a local pond, stream, or ditch to catch whatever I could. Three-spined sticklebacks were my favorites. In the spring, male sticklebacks develop bright red breasts. The color can be so intense you’d swear they were bleeding heavily. If you put two male sticklebacks in an aquarium, as I did, the fish would fight until one had established dominance.
I discovered you didn’t need to be a male stickleback to get into a fight. For some reason, I decided to run a piece red licorice along the aquarium glass. The resident male stickleback went nuts and tried to kill it. Intrigued, I tried with several other objects. It turned out only one thing sent the stickleback into a frenzy — the color red. The stickleback’s Umwelt was color specific. The object’s shape and to a large degree its size were irrelevant.
So what does this have to do with weird-looking flies? From an evolutionary perspective, the only thing that matters is that an organism’s Umwelt allows it to reproduce. If you don’t reproduce, your Umwelt dies along with your genes. The Umwelt of trout and countless other species of fish has been shaped by millions of years of evolution. Hooks, meanwhile, have been around for only a few thousand years, and fishing with flies has likely been practiced for less than two thousand. It’s unlikely there’s been enough selective pressure on any species of fish for them to have evolved an Umwelt that recognizes hooks. Simply put, fish see the hook, but their brain ignores it.
This doesn’t mean trout and other species of fish in heavily fished catch-and-release waters don’t develop a negative reaction to certain aspects of fly fishing. It’s what makes these waters so fascinating. Drag, for instance, is a well-known way to not catch trout, and a clumsy cast can totally freak them out. But a well-tied fly that is presented properly still catches fish, even on the world’s most challenging waters. In addition, countless fly fishers have caught trout on bare red hooks, and bonefish have taken plain steel hooks. If the hook was really a problem, fly fishers would have developed radically different patterns long ago.
Using Slip-Ons
So why bother using slip-on flies, when regular patterns are clearly very good at catching fish? For a lot of fly-fishing scenarios, they don’t offer any real advantages. But there are times and places where slip-on flies provide a slight edge. When you start to fish challenging waters or find the fish are being unusually difficult, changes in tackle and technique can have a significant effect on fishing success. This is when a slip-on fly may be the ticket.
Picking Pockets
You can have a lot of fun and success working your way along a stream, placing nymphs into every pocket or run. Whether you are fishing one fly or more, the setup needs to get down to the fish, which are usually close to the river bed. Your fly should occasionally tick the bottom to ensure it’s in the hot zone. This sounds great, but the reality is that each section of water can have different hydraulics and depth. With judicious mending or competent tight-line techniques, you can adjust to these changes to a certain degree.
But there’s a limit to how much control you can exert with rod and line. Quite often, a section of water will require a heavier or lighter fly. We know this, but decide tying on a new fly is just too much effort. Instead, we fish the stretch halfheartedly and move on to the next piece of fishy-looking water.
This is where the slip-on design can help. Since you don’t have to tie a new knot, fly changes take just seconds. This means you are more likely to change flies and fish every piece of water thoroughly. In addition, if you do get hung up and damage the hook, you still have a perfectly good fly. Just tie on a new hook, slip on the fly, and carry on fishing.
Lighten Up
Slip-ons allow you to use a pattern that weighs less than a regular fly of similar size. This can be especially helpful when you are fishing with delicate cripple or spinner patterns that need to sit right in the surface film. The secret is to make the fly’s body from monofilament or fly line and to use a smaller hook. For example, a size 18 hook works on flies that are usually tied on size 12 hooks. Lightwire scud-style hooks work well for this application. In addition to the slip-on being lighter than conventional patterns, the mass of the smaller hook is located at the front of the fly, where hackle and floatant-infused dubbing provide more buoyancy.
Backwards Flies
For stuck-in-the-shuck and emerger patterns, it may make sense to hang the hook from the fly’s rear end. This focuses the weight of the hook at the back of the fly, which helps the shuck/body break through the surface film while the rest of the fly sits in and on the film. In addition, the rear-mounted hook can help take the tippet down with it, eliminating the light-flaring effect caused by tippet deforming the surface film. As with regular patterns, the tippet is more likely to sink if you apply sinkant or Fuller’s earth to its final few inches.
The jury is out on whether tippet flare matters to the fish, but many experienced dry-fly anglers feel it does. There’s no doubt the effect can radically change the appearance of a fly from below, especially when the sun is lower in the sky.
The slip-on fly design makes it relatively easy to create a rear-mounted fly. If you twist a piece of the silicone cord, it will form a great-looking segmented body with a stretchy eye at the end. Just tie this shuck/abdomen onto the fly and, if necessary, color it with a Sharpie marker.
Fat Flies
On flies that have a fat body, like some baitfish, frog, and terrestrial insect patterns, the effective gape of the hook can be reduced by as much as 50 percent, which can decrease the hooking efficiency of the fly. If you find you get grabs, but not many hookups, girth may be the problem. The slip-on design positions the hook ahead of the fly so that the point and gape are completely exposed. With no materials to get in the way, there’s a greater chance a grab will become a hookup.
This is actually a fly-fishing adaptation of the carp angler’s hair rig. Carp, like trout, quickly reject any item that doesn’t feel or taste right. Carp fishing can make steelheading seem easy, with days between bites. Not surprisingly, carp anglers are highly motivated to ensure their rigs have the optimum hooking efficiency. Kevin Maddocks and Lenny Middleton, two British carp nuts, developed a system where the bait is separated from the hook by a short piece of thread. This setup produces significantly more hookups than when the hook is partially buried in the bait. Many carp addicts consider the hair rig to be one of the greatest fishing inventions.
Another issue with fat flies is that they can make hook removal more difficult. When the fish has taken the fly farther back in the mouth, the extra material can interfere with the correct positioning of a hook-removal device. It may take only a few more seconds to remove the hook, but those seconds can have a profound influence on the survival of the fish. When it comes to catch-and-release fishing, seconds count.
Weedless
When you are working flies close to weed beds or into gnarly structure, it really helps to have the point shielded so it doesn’t snag bits of weed or get stuck into something really solid. The slip-on design can do this, using an adaptation of a bass angler’s plastic worm setup.
First of all, select a hook with an eye that’s in line with the hook point, such as bass worm hooks, jig hooks or Kahle (catfish) hooks. Instead of hanging the fly off the bend of the hook, pull it up to the hook eye. The fly itself is tied with a soft, compressible hair or wool body, which fills in most of the space between the shank and the point. The final step is to apply thin coat of fabric paint, Elmer’s washable clear glue, or Aquaseal to the top of the fly.
Slip the fly onto the hook and arrange things so that the hook point is just above the body. When everything looks good, give the body and silicone eye a gentle upward push. The point will form a tiny, submillimeter depression in the paint/glue surface. This gives you a weedless pattern that exposes the point the second a fish clamps down.
Storing Slip-Ons
As you might imagine, the lack of a hook makes clip or slit-foam fly boxes a poor choice for storing slip-ons. Thankfully, regular compartment style fly boxes work great. Just keep one or two compartments free for a few ultrasharp hooks. For larger streamers, forget the box and use Ziploc bags. This can free up valuable pocket or pack space.
Sometimes, it’s nice to have a selection of go-to flies that you can get to without opening packs and fly boxes. This is where most folks use a fly patch. Obviously, that won’t work with slip-ons. There is simple solution. Just thread a few flies onto some thick mono and attach this to your vest, lanyard, or pack with a safety pin. The elastic eye constricts against the mono, and friction keeps it in place. Cut the end of the mono at a sharp angle so you can thread the fly on quickly and easily. If you are worried that extra-heavy flies might slip off, just crimp a V into the end of the mono.
Not the Next Big Thing
Let’s be honest, slip-ons are probably a bit too outside-the-box for regular fly fishers. This means commercial fly companies won’t bother with them, and they aren’t going to show up in fly shops or online catalogs. They’ll remain the province of adventurous fly tyers and die-hard fly fishers. I see this as a good thing. It means some of us will have a secret weapon when the fishing gets tough.
