Fly Of The Week
Biot Midges
Biot Midges
By Ralph D'Andrea, Colorado, USA

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Biot Midges

This week's fly is really an easy-to-tie family of flies that imitate different forms of the same insect. It shows how you can add a single material in strategic places and come up with something that just might match whatever the fish are taking at the time. Maybe it will give you an edge.

Except for a few places that close to protect native cutthroat populations, there is no closed season for trout fishing in Colorado. That means we fish midges a lot, because there really isn't much else happening during the winter. During the first week of January this year, a friend and I got cabin fever pretty bad and decided we needed to go fishing. He took me to a place I had never fished before. Not a GREAT place, mind you, the water was pretty murky and there were other fishermen on the water, but in January at this elevation you are happy just to find liquid water.

When we got there, the afternoon midge hatch had started and there were dozens of fish rising below every riffle. Small rainbows, 8-14 inches, escapees from a nearby hatchery who grew up in the stream, but we all know there are no BAD fish. We knew they had to be taking midges, and deduced they had to be taking emergers for a number of reasons. We fished everything we had: Palominos, WD-40s, RS-2s, anything that we thought would work. After several hours, he had two fish and I had one. Clearly, we weren't throwing something that interested these fish. After another trip down to the same spot with similar results, I brought my trusty 50 cent aquarium net, waded into a riffle, spooked all the fish, and figured out what they were eating. Tiny little black midges, size 24. I saw empty shucks, I saw pupae, I saw emergers. Whole rafts of them. The fish were just slurping them off the surface. When I went home that night, I decided to tie up something that looked like what I saw.

Any good "match the hatch" book will have a picture of a midge pupa, probably taken through a microscope so you can see the head, thorax, wing pads, maybe even count the body segments. The best way to use one of these pictures is to hang it on the wall and look at it from across the room, because what the fish sees is going to be less than a quarter inch long and silhouetted against the sky, and he'll have to react to it within a second or two or it will be past him in the current. If trout are taking midges, they will usually take anything that looks almost right and spit it out if it turns out to be inedible. The most important thing in imitating something this small is to focus on the basics: size, color, profile. From across the room, your midge picture is going to show you that your midge needs to have a skinny little segmented abdomen, a beefy thorax that you can't really tell from the head, and not much else. Look at midges in the water from about 3 feet away where the fish first react to them and you'll see the same features.

What I tied that night was a basic biot midge. It has a skinny, segmented body; a thorax that's between 1/4 and 1/3 of the total length of the body; and not much else. I tied black ones in size 22 and 24, then went fishing. I started getting strikes on every other cast.

Figure 1 shows the basic version of this fly and three variations I cooked up because we don't have enough else to do around here in the winter. Also, because the water is clear some days and you can sometimes see the gills on the midges. All are pictured at size 20. Clockwise from the top, there's the Basic Biot Midge, a pupal form that has gill tufts fore and aft, an emerger form that has the remnant of a gill tuft in the front and a stubby emerger wing, and an adult form that has a wing that imitates the body-length delta wing of an adult midge. They are all tied about the same way. The basic midge is extremely simple to tie; the variations add only one more material, CDC. None of these flies are "new" and I claim credit for none of them. Since tying them, I have seen similar flies in a lot of books. But then we all know there are no new flies.


Hook:  Dry fly hook, 18-26 (flies pictured are size 20).

Thread:  To match biot and natural.

Abdomen:  Goose or turkey biot, black, gray, brown, olive, tan or red, to match natural.

Thorax:  Superfine dubbing to match biot or tying thread.

Gills or wings:  White or light dun CDC puff (see tying instructions).

Tying Steps:

1. If you are tying the basic, emerger, or adult form, start the thread just behind the eye and wrap a thread base to the zero point of the hook.

1a. If you are tying the pupal form, tie on about a quarter of a puff of CDC right where you started the thread so that the tips extend about two or three eyewidths forward of the eye of the hook. Wrap it down as you wrap the thread base, then tear or clip the butts one or two eyewidths rear of the zero point. You have just formed both gill tufts.

2. Tie on and wrap a biot body of the desired color as explained in this week's Tying Tips. Wrap it as far forward as you can without crowding the eye, tie it off, and clip the butt. If you're tying the basic form, skip to Step 4.

3a. If you are tying the emerger form, tie on about a quarter of a puff of CDC where you finished the biot so that that the tips extend about two or three eyewidths forward of the eye of the hook. Wrap it down with three or four thread wraps, and clip or tear the butts at mid-body. You have formed the gill tuft and emerger wing.

3b. If you are tying the adult form, tie on a generous amount of CDC (about half a puff) where you finished the biot. The tips should project rearward to mid-bend of the hook. Clip the butts flush with the tying thread. You have just formed the wing. When it's wet, it will lay down in the film and look just like the delta wing of an adult midge.

4. Form a thorax with a small amount of dubbing or with your tying thread. If you choose to use dubbing, use only a few strands of superfine, just enough to see on the thread, twist it on tightly, and dub only about an inch of the thread. The choice of dubbing or tying thread is up to you. Some people dub faster than they wrap thread. The objectives are to make the front 1/4 or 1/3 of the body about twice the diameter of the rest of the fly and to cover up the places you tied off the biots and tied in the other materials.

5. Whip finish, clip the thread, and you're done.

More on Biot Midges:

I chose a dry fly hook for these flies for a couple of reasons. First, I've spent a lot of time watching midges. Most species (not all, but most) emerge in the film parallel to the surface of the water, so I wanted a straight shank. Second, since I was planning to fish this fly in the film, I wanted light wire.

Biot Emerger

Roy Palm of Roaring Fork Anglers ties a very effective biot midge emerger (above) that uses the same theme, but he finishes off the Basic Midge with a sparse wrap of hen feather at the front. I've fished it, it works. When I tie it I use starling.

Each of these flies is totally impossible to see in the water and fish take them gently, so some sort of strike indicator is necessary. I fish them when the fish are looking up - i.e., when some sort of rises are evident. I fish them on about a foot and a half of 6x or 7x tippet tied to the bend of an ugly, high-floating dry fly that I can see (think Humpy, Wulff, Stimulator here). I grease the entire length of the tippet to keep the fly in the film.

I have to confess that although I have fished and caught fish on all of the forms presented above, I've fished the Basic pattern most often. It has all the essentials: size, color, profile. If you use tying thread for the thorax, there's only one material - the biot. Although I'm not a guide, I'd have to call it a Guide Fly: catches fish, cheap, and you can tie two dozen of them an hour even after a beer or two.

Tie some up in different colors and sizes. When you see midges on the water, try them. You might like them. Let me know if they work as well for you as they do for me. ~ Ralph D'Andrea

Sources Used:

Best, A.K. (1989): Production Fly Tying. pp 67-68.
Best, A.K. (Date unknown): Biot Miracle Nymph. cle%20Nymph
Lesson, Ted, and Jim Schollmeyer (1999): The Fly Tier's Benchside Reference. pp 112-114
Mason, Harry (2000): Tying with Biots.

For more great flies, check out: Beginning Fly Tying, Intermediate Fly Tying and Advanced Fly Tying.

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