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Why You Should Be Fishing More Leech Flies

Leeches cause trout and bass to abandon caution.

Why You Should Be Fishing More Leech Flies

Historically, fly tiers and fly fishers have tied and used leeches that are too large. While there are 3-inch and larger leeches out there, trout most commonly feed on leeches a ½ to 1½ inches long. This is where Mayer’s Mini Leech and Mini Leech Jig fill a void. (Landon Mayer photo)

This article was originally titled "Flies that Don't Suck" in the Feb/March 2022 issue of Fly Fisherman magazine.

A word for “leech” can be found in almost every language on Earth. That’s because they are everywhere. Leeches are aquatic worms that are members of the annelid (ringed or segmented worms) phylum, and are found on every continent except Antarctica. This makes leeches extremely important in fly fishing, as it is always leech season. Whether you are fishing a lake or river, in high or low water, winter or summer, there is a good chance you can mimic this common food supply and catch fish.

Some leech species can grow up to 18 inches long and live as long as 20 years. That sounds like something from a horror movie. Thankfully, most of the leeches of interest to fly fishers live in fresh water and are commonly ½ inch to 3 inches long—plenty to provide a hearty meal for trout and many other gamefish. With a color palette ranging from black to tan, leeches can hit every shade in between.

Leeches can be found drifting in moving and still waters, or swimming like a ribbon. I will never forget sitting on the bank of Spinney Reservoir one day, eating lunch with my good friend and client John Johnson. Pointing toward the water, John asked: “What is that? It’s moving really fast.”

I looked down, and to my surprise a 3+-inch leech was swimming a few inches below the surface. I flipped my uneaten sandwich in the air, and with the sandwich container I captured the racing ribbon. I was soon sitting with John watching this huge trout meal swimming around in the container.

This incident inspired the design of the Mayer’s Mini Leech, Mini Leech Jig, and Mini Leech Jig Radiant. Tied with micro pine squirrel extending from a thick ostrich herl collar, these patterns imitate the tapered bodies of leeches. The jig versions are tied on 60-degree jig hooks, and when attached with an improved clinch knot, they balance in a horizontal position, just like a real leech.

Why You Should Be Fishing More Leech Flies
Leeches come in three natural color schemes: rust, olive, and black. Carry Mini Leeches and Mini Leech Jigs in these colors in sizes 12 through 16 and you’ll be prepared to catch trout in both rivers and stillwaters. (Landon Mayer photo)

Leeches as Medicine

Leeches are parasitic worms that attach themselves to other animals to drink blood. Leeches can also reportedly reduce swelling in tissues and promote healing. For these reasons, they have been used in medicine in many parts of the world for at least 2,500 years. Pliny the Elder reported the use of medicinal leeches in the Roman Empire. In 19th century Europe, the demand for medicinal leeches was so great that they were actually farmed, and some people in Britain worked as professional “leech gatherers,” collecting wild leeches to sell for medicinal use. Leeches are still used today for specialized medical purposes, such as improving blood circulation in microsurgery.

Leeches breathe through their skin and feed on the blood of whatever is around, including fish and snails. It seems ironic that the very creature that waits in vegetation to scam a quick bite from a passing fish can so easily have the tables turned on it and become a meal.

Because fish eagerly consume them, leeches have long been favorite baits. The first designs of flies to imitate leeches arguably date as far back as the early 1800s. I personally believe that the black Woolly Bugger—an iconic pattern created by Pennsylvania’s Russell Blessing in the late 1960s—is still one of the best leech imitations ever. Its chenille body, palmered soft hackle, and marabou tail make the Woolly Bugger look alive in the water, just like a swimming leech.

Other standout leech patterns include the Goat Leech, Simi Seal Leech, Egg-Sucking Leech, Bunny Leech, and Balanced Leather Leech. [See Charlie Craven’s tying instructions for the Balanced Leather Leech in the Feb.-Mar 2021 issue and on our Fly Fisherman magazine YouTube channel. The Editor.]

Mentioning the Egg-Sucking Leech brings up an obvious question: Do leeches actually suck eggs? I don’t believe so, but you can’t go wrong putting two of your favorite snacks on the same plate. A bright spot on a leech really helps attract attention, especially from migratory fish with a life history of feeding on eggs. That’s the idea behind my Radiant Leech—it’s a smaller, denser version of the old Egg-Sucking Leech, and it swims in a jigging motion with the hook up. It’s a logical evolution for a pattern that has caught fish on many continents for many decades.

Matching the Leech "Hatch"

Another great advantage is how versatile leech patterns can be. Whether you’re imitating a leech with the right size and color, trying to match a garden-variety leech in the general size range, or simply fishing a leech fly as an attractor with movement and swinging motions, selecting the right pattern usually involves choosing among three main colors: olive, rust, and black. These three colors should cover the spectrum of leeches you’ll encounter, from light to dark and most in between.


Why You Should Be Fishing More Leech Flies
Leeches work as well in rivers and streams as they do in stillwaters. You can fish leeches deep, or you can rig them as droppers under high-floating indicator dry flies. This allows you to drift leeches along feeding lanes and into shallow pockets where trout are feeding. (Landon Mayer photo)

One of my favorite methods for fishing leech imitations is trying to match what I see in the water or hidden in clumps of vegetation. Trout that are hunting for a meal pursue small patches of vegetation, knowing that the green, tan, or brown clumps are often full of insects and other creatures, dead or alive. I first saw this on the San Juan River in 1999, when a local angler showed me an olive fly that resembled a small leech and told me that he’d been killing it on that pattern all week.

While I was using his flies, I noticed small clumps of vegetation drifting downstream. Then, to my surprise, I watched a fish I was stalking race over and eat a clump. Soon I noticed many fish were doing it. Some would swallow a clump whole, while others chewed on it like a piece of gum before spitting it out.

That afternoon, I took the time to sift through handfuls of vegetation from the river, and then the light bulb went off. The clumps were packed with midges, and the trout saw them as veritable platters of food. A small olive leech isn’t a bad imitation of drifting vegetable matter, and I have used this technique on numerous waterways for years with great success. When flows are higher than normal, match your fly to the color of the vegetation with a small leech pattern (1 to 2 inches) with no flash. The trout will be searching for the next dislodged and drifting clump of plant matter, and you might get a solid hit.

Rigging a Leech Fly

One of my favorite two-fly rigs for the fall is a hopper with a Mayer’s Mini Leech Jig drifting below. The Mini Leech Jig is my go-to anchor fly for nymphs, dry/droppers, or as a solo drifting streamer imitation. Tied on a Umpqua XC400BL-BN hook with a slotted tungsten bead, the Mini Leech Jig uses a micro pine squirrel Zonker strip tied with the fur side against the hook shank with an ostrich herl collar. The hair and herl provide enough buoyancy that the pattern balances nicely while suspended in the water.

Tied in sizes 12 to 16 and in colors such as sculpin olive, rust, and black, the Mayer’s Mini Leech Jig is a pattern you can rely on for streams, rivers, and stillwaters. This pattern effectively matches natural leeches and often triggers aggressive strikes from hungry gamefish.

To fish a Mayer’s Mini Leech Jig as part of a hopper/dropper combination, I use a smooth casting stroke and wide loop because it is essential to keep the two flies separated in the air and in the water. Think of the backcast as a smooth pull, and the forward stroke as a smooth push. This helps you slow down and concentrate on each stroke, which in turn reduces false casts and produces more accurate deliveries.

After you stop on the forward cast, drop your rod tip slightly, pointing your thumb toward the target to turn over the leader and the flies completely. Your rod tip must travel in a straight plane to cut through wind and make good loops, and that allows the flies to straighten out instead of collapsing and bunching together on the water.

Presenting a Leech Fly

Many anglers have asked me whether I prefer to dead-drift my leech flies or swim them. The answer is yes.

We’ve all seen giant trout charge a swimming streamer and then suddenly refuse the fly and turn away. Sometimes, the same fish will chase the fly over and over again with no hookup. Using a slackline method can quickly change a fish’s mood. It may sound crazy, but often when a trout is pursuing swimming prey, if you “freeze” the fly and allow it to pause or drift with the current, you’ll get more connections. It’s easier for the fish to pounce, and you’re not pulling the fly away from the fish.

I believe that fish in many situations prefer an injured meal over something that is completely dead and lifeless, or actively escaping. The best way to make your fly seem alive—yet easy prey—is to add a pause to your retrieve. This pause is when a large predator knows it can kill the mouse, baitfish, crayfish, or leech. This is true whether you’re talking about smallmouths, largemouths, carp, pike, or trout.

When I’m guiding, I often use the word “freeze” because most anglers react to that word faster, but it is essentially a pause.

Why You Should Be Fishing More Leech Flies
Leeches are freshwater parasites that suck blood. Like mosquitoes, they use an anticoagulant to keep their food flowing. They have been used medicinally for centuries, and are still used today to improve circulation and reduce swelling. (82376702 / Leeches  Alexan24 | photo)

It will at first seem counterintuitive to freeze (pause) when a trout is following, but once you do—and you see the kill behavior from the trout—you will forever become a believer. Also, be prepared to regain tension after the strike, and pay attention to the angle you need to set the hook effectively. Set in the opposite direction of the trout’s feeding movement. This will position the fly in the corner of the jaw giving you a more secure hookup.

Most fly fishers are very familiar with the importance of a drag-free drift while dry-fly fishing or nymphing.

A drag-free drift helps imitate food items like aquatic insects, and it can help get your flies deeper. But leeches can actively swim, so moving the fly provides realism and it also allows you to move and position your flies accurately in a trout’s viewing lane.

When I present to fish in deep water—especially along drop-offs below the shallow water at the head of the run—I overweight my rig for the deep water. I land my flies 2 to 3 feet upstream of the drop-off, and twitch my flies with quick, 1 to 2 foot sideways movements with the tip of the fly rod. This movement in shallow water helps me avoid snagging bottom and allows me to draw the flies to where I think the trout are holding. Then I “freeze” the fly when it falls over the drop line into deeper water where I know there are bigger fish.

I draw an imaginary line from the trout’s head upstream to where my flies should land (similar to a golfer lining up his putt). This gives me the confidence of knowing my flies will enter the trout’s viewing lane at the right depth and moving correctly—instead of guessing on each consecutive drift. If I cast along this imaginary line, I can twitch my flies back on track.

If a large fish is nestled right along the bank in a nook where it’s impossible to get a drift like this, I cast slightly above the trout. Once the imitation drifts into the viewing lane, I use a twitch to entice the fish to come out of the cover and take the fly. Fish like this often won’t move for a tiny insect, but they will come out from their lairs to crush a leech.

Trout, bass, and many other freshwater gamefish in both rivers and lakes love to feed on leeches, and they fall for these techniques regardless of water flows or seasons. So tie on a good leech pattern, and hang onto the rod!

Mayer's Mini Leech

(Click here for step-by-step instructions)

Why You Should Be Fishing More Leech Flies
Mayer's Mini Leech

HOOK: #12-18 Tiemco 2488H.
THREAD: Black 8/0 UNI-Thread.
BODY: Black/red Krystal Flash.
WING: Black/brown micro pine squirrel.
THORAX: Black/brown ostrich herl (large).

Mayer's Mini Leech Jig

Why You Should Be Fishing More Leech Flies
Mayer's Mini Leech Jig

HOOK: #12-18 Umpqua XC400BL-BN or Umpqua XT500.
THREAD: 8/0 UNI-Thread.
BEAD: Black slotted tungsten bead (2.3-3 .2mm).
BODY: Black/green/root beer UV Krystal Flash.
WING: Black/olive/brown micro pine squirrel or micro mink.
COLLAR: Black/brown/olive ostrich herl (large).

Mini Leech Jig Radiant

Why You Should Be Fishing More Leech Flies
Mayer's Mini Leech Jig Radiant

HOOK: #12-18 Umpqua XT500 or Umpqua XC400BL-BN.
THREAD: White 70 UTC.
BEAD: Pink slotted radiant tungsten bead (2.3-2 .8mm).
BODY: Pink Krystal Flash.
WING: White micro mink.
COLLAR: White ostrich herl (large). 
Note: These are some other favorite color combinations: black wing and herl/purple bead, white wing and herl/pink bead, black wing and herl/orange bead, rust wing and herl/brown bead, olive wing and herl/olive bead.

Landon Mayer ( is a Colorado fly-fishing guide and Fly Fisherman contributing editor. He lives with his wife Michelle and their four children in Florissant, Colorado. His most recent book is Landon Mayer’s Guide Flies: Easy-to-Tie Patterns for Tough Trout (Stackpole Books, 2022).

Why You Should Be Fishing More Leech Flies

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