Welcome to Not Quite Entomology

Welcome to Not Quite Entomology! This is a different approach to matching the hatch, or learning which insect the fish are really eating. The flies and methods to make it all work will be here as well. We hope this series will inspire you to go out, look on top of and under rocks, check the stream-side vegetation, really investigate your favorite water and learn which are your local trout's favorite foods!

Midges - Diptera

By Ralph D'Andrea

Lee's Ferry Midge
Many flyfishers use the term 'midge' to describe any tiny fly. In fact, in some fly catalogs, you can find 'Adams Midges' which are perfect little Adams dry flies tied down to size 26 or 28. However, a 'midge' is actually a distinct variety of insects of the order Diptera (true flies), family Chironomidae. All true flies have only two wings, which is the big identifying feature of these insects.

There are lots of different kinds of bugs in the order Diptera. In North America alone, there are more than 16,000 species; more than 5000 of them have aquatic larval stages. The Chironomids represent about 175 distinct genera and hundreds of North American species of the aquatic Diptera. Quite simply, they are everywhere, and they are an important food source for trout. (More on Chironomids next time.)

Many eastern flyfishers I talk to aren't in the habit of fishing midges, but virtually all of the flyfishers I talk to in my native Colorado fish midges fairly often. I believe there is a reason for this. Most eastern states have open and closed trout seasons; when it is trout season there are usually other flies on the water. In Colorado and some other western states, there is no closed season. So we sometimes fish in the winter when midges are the only thing hatching. And midges do hatch year-round. One day last February I was fishing on the Colorado River, and the foam lines in the shallows were brown with midge shucks. I have seen midges hatch in below-zero conditions, surviving only in the thin warm layer of air within one or two inches of the water's surface. Any midge brave or stupid enough to reach an altitude of 3 inches froze solid.

larva, Chironomus attenuatus In the west, midges catch lots of fish. Big fish. How does something so tiny catch a big fish? The best analogy I have heard is the 'popcorn shrimp' analogy. Popcorn shrimp taste great, but it takes a lot of them to fill you up. Trout eat them by the thousands. Anything that trout eat by the thousands is worth fishing. Midges are ubiquitous, trout instantly recognize them as food. Even spooky 'catch and release' western tailwater trout will take a midge pattern without a second look because they are so used to seeing them. I bet eastern fish would too.

Midges go through complete metamorphosis. That means that unlike mayflies and stoneflies which have only a nymphal aquatic stage, midges have both larval and pupal aquatic stages. They are available to trout in both of these stages, as well as in emerging, mating, or egg-laying adult stages. Midges are found in lakes and streams and can be fished in either environment. The midge larva shown above is 12 to 17 mm in length, (less than 6/16ths).

Midge larvae are tiny, free-swimming, wormlike creatures characterized by evenly-segmented bodies with no projections and distinct heads. There may be 'prolegs' on the first and last body segments, but these are hard to see. They are commonly black, brown, olive, gray, or red. They typically live on, in, or near the bottom but are often washed out of their preferred safe locations and are available to feeding trout.

Midge pupae also have segmented bodies, but have gill filaments at the head and tail ends and small wingcases folded tight against the body. They are available to feeding trout as they begin their swim to the surface to emerge. Being poor swimmers, they rise slowly to the top, may fall back to the bottom, and generally take quite a long time to reach the surface film.

Adult midges look like gnats or mosquitoes but have no biting parts. I have seen them in black, brown, and gray, in sizes smaller than 32 up to (believe it or not) size 12. They emerge from the surface film and live several hours during which their sole purpose is to mate. They typically mate in clusters on the water, and also return to the water to lay their eggs. This means they are available to trout during emergence, mating, ovipositing, or spent stages. Wind and chop that break the surface film speed emergence; still, heavy air creates a 'stickier' surface film and makes the adults more vulnerable. Some still night when trout or bluegills are dimpling your local pond by the thousands and you can't see what they are eating, look for midges.

Each life stage of midge is fished differently. Midge larvae are typically fished dead-drift, on or near the bottom, often as a trailing fly behind an attractor such as a bead-head nymph or egg pattern. Split shot to get them down and strike indicators to see subtle takes are de-rigueur. Because they are small and hard to see, they are less effective when fished in a single-fly setup. But once another fly has caught the attention of a trout, they will often take the midge larva preferentially.

Midge pupae are fished as a trailer behind a dry fly or on a greased leader. In lakes, a slow 'strip and pause' retrieve technique will cause the pupa to rise to the surface and fall back down just like the natural. Cruising, upward-looking fish will see them and hammer them.

Emergers are fished in the surface film, either on a greased leader or as a trailer behind a dry fly. Trout might take midge emergers with either the sipping or splashing rise form, depending on how fast the naturals are getting away.

Chironomus attenuatus adult

Adults are fished as any other dry fly. I tend to not fish individual adult midge patterns very much for a couple of reasons. First of all, they are tiny and extremely hard to see. Second, midges do not have tails, so a realistic imitation (tailless) won't float very well. When adult midges are on the water, I tend to fish a Griffith's Gnat--pattern that imitates their clustering mating behavior. A size 14 or 12 Griffith's Gnat looks like a mating cluster of couple of dozen adult midges; trout are lazy and like to expend as little energy as possible when feeding and so they will often sip the whole cluster at once. This is a deadly effective fly when there are adults present.

There are hundreds of published midge patterns representing each stage of a midge's existence. Most of them work quite well. The patterns listed below are just a sampling of effective ones:

    Larvae: Lee's Ferry Midge 'Magic' midge, Biot Midge.

    Pupae: Serendipity, Owens' Thread Midge.

    Emergers: CDC Midge Emerger, RS-2.

    Adults: AK's Quill-body, Griffith's Gnat. ~ Ralph D'Andrea

    For more on Midges, with more fly patterns click here.

    Credits: All illustrations from Aquatic Entomology by W. Patrick McCafferty, published by Jones and Barlett.

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