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Feature Trout


by Ross Purnell, Editor   |  August 29th, 2012 0

Photo: Greg Mcdermid

Where I first learned to fly fish, everyone said, “Big flies catch big fish,” and that was true. But where I fish now—on tough, technical tailwater trout fisheries like the San Juan, Green, and Frying Pan Rivers—big flies catch mostly stupid little trout.

There are times on some of these tailwaters, most often during the summer, when trout feed on “normal” fare like caddis, mayflies, and sometimes even large terrestrials. But in most of these fertile, dam-released rivers, the vast majority of the aquatic insect population is made up of “midges”—tiny two-winged flies of the order Diptera, of which there are more than 100 species in North America.

Trout feast on these midges all year long, and in the late fall, winter, and early spring, they feed on them almost exclusively. These circumstances require special tactics and tiny flies that imitate the prevalent midge population. I consider these tailwater midge hatches to be one of fly-fishing’s highest plateaus To sight-fish to enormous trout with tiny flies and gossamer tippets is a true test of your angling mettle.

Midge Patterns

To be a proficient midge fisherman, you need a range of fly patterns that imitate every stage trout prey upon. You need to know what fly to use, and when to use it. Things can change suddenly during a midge hatch, or combined midge hatches, especially on productive water where large trout have the luxury of targeting specific stages of specific insects. Sometimes you’ll tear up the river on a #20 red larva imitation, and then suddenly the fish switch to dark brown #24 pupa. If you can’t recognize and make the change, the fish will get the better of you.

Midge larvae. Even the best anglers sometimes overlook the importance of midge larvae. Midge larvae are long and slender with a uniform profile. The best imitations are nothing more than thread—twisted to create a segmented look—wrapped on a curved hook. Andy Kim’s Yong Blood [For tying Andy Kim’s midge patterns see Fly Tier’s Bench in this issue. The Editor.] and Bear Goode’s Sparkle Larva are the best examples of these types of patterns. Anything with a bead or with a pronounced thorax has the wrong profile. Take a seine or net with you and match your pattern to the specimens in the stream.

Midge pupae. Think long and slender for midge larvae, short and squat for midge pupae. The pupa’s thick thorax contains the adult’s developing wings. My favorite pupa imitation is Andy Kim’s Yong Special, because it’s the closest replication of the originals I see most often on the San Juan, Green, Frying Pan, and other rivers. Old classics such as the Black Beauty, Miracle Nymph, or Brassie work as well. On the Colorado River at Lees Ferry, the Beadhead Zebra Midge is the ticket, especially out in deeper water.

Emerging pupae. When midges begin to emerge, their budding wings become prominent, and they sometimes carry gas bubbles that trigger trout to feed. This phase of the transformation has been studied extensively by some very good anglers who have developed deadly imitations. Rim Chung’s RS2 pattern was developed for finicky South Platte trout and has been widely adapted on the San Juan and elsewhere. The WD-40 is an emerging-midge pattern developed by John Engler on the Frying Pan, but it works almost anywhere there are midges. Johnny Gomez’s Johnny Flash has the profile of the WD-40 and the emerging wing of the RS2.

Single adult. As with all midge fishing, fly size is the critical element, followed by the shape and color—in that order. There are many excellent patterns out there to choose from. I have had good success with just a thread-body fly with two turns of grizzly hackle. That’s all I can tie in a #24 or smaller. My friend Rick Takahashi ties a fly biot midge that is simply sinister to trout, and I swipe as many as I can out of his fly box when he is not looking.


The best midge fishermen have great powers of observation and a meticulous, predatory approach to their angling. Andy Yong Kim—a guide on the San Juan River—is one of these trout hunters. Kim is either changing flies, adjusting weight, changing his leader length, or landing a fish. There is very little wasted effort or fruitless casting involved in his technique. He believes far too many fishermen string their rods at the parking lot and cast the same nymph rigs all day long. They may enjoy some success during parts of the day, but they would catch more fish if they modified their tactics as conditions changed.

If you are serious about fishing midge hatches, your first course of action will be to sample what’s in the water with a seine or a small aquarium net. Early in the day, you are likely to see more midge larvae than anything else.

Most of the time, trout feed on midge larvae near the bottom, so you need a nymph rig that delivers the fly to the fish effectively. If you want your fly right on the bottom, the distance between your strike indicator and terminal fly should be about 11/2 times the depth of the water. I think everyone but the most novice angler has heard this advice, but most people refuse to act on it. They still set up a 9-foot leader in the morning and fish with it all day just because it’s convenient. That’s fine if you are out for the fresh air, but if you want to make every cast count, you must alter your leader to suit specific water depths.

I recommend a moveable yarn indicator or a small cork or foam indicator held in place with a toothpick. Putty, stick-on foam indicators, or loose yarn tied on with a slip knot are fine for static fishing, but can be frustrating nuisances when you move your indicator thirty times a day or more. An indicator that moves quickly and stays in place after you move it will make your day more enjoyable.

The other key to getting your fly to the fish is weight on the leader. Midge flies are too small to effectively use internal weight, so you must carry a good selection of micro-split-shot in various sizes. As with the leader length, you must constantly change the weight on your leader to match the water depth and speed you are fishing in.

Weight on your leader helps you get down to where the fish are, but it also interferes with your ability to detect strikes because it creates a dead zone between the weight and the rest of your leader. Lighter weights reduce this effect, so I recommend using as little weight as possible for the water type. Spreading the weight along the leader also reduces the “anchor” effect. If you need a lot of weight, it’s best to distribute a few pieces along the leader, rather than putting on one big shot in a single spot. I fish two flies and always position the top fly above the weight so I have direct contact with at least one fly.

Heavy weight gets your flies down to fish in fast water but can also act like an anchor, creating undetectable subsurface drag. Outfitter and local expert Tim Heng showed me how to defeat this type of drag on the Frying Pan River. My friend and I showed Heng a trout we had spent hours trying to catch, and he promptly hooked and landed the 12-pound leviathan in three casts. He used similar weight to get the fly down to the level of the fish, but when his fly was about 12 or 18 inches in front of the fish, he “hopped” the weight off the river bottom, creating slack in his tippet between the weight and the fly. That’s all it took for the trout to inhale his #20 red midge larva imitation.

In a two-fly rig, I tie a pupa on top, because the real thing is likely to be higher in the water column than a larva. When fish begin to key on pupae, they start taking the top fly more than the bottom fly, but there are other signs. You’ll begin to see adult midges on the surface of the water and rocks along the shore. If you are sight-fishing, you’ll notice the fish are more active. They’ll move side to side more frequently, gulping pupae bound for the surface, and they’ll often move into different water types to take advantage of the hatch.

When a hatch really gets going, trout suspend in the water column, sometimes just inches under the surface, and gorge on emerging pupae. It’s important to pay attention to where the fish are feeding, and if the fish are “up” on midges, you’ll have to drastically reduce your leader length. You can do this by moving your strike indicator down the leader toward the fly or by removing the indicator altogether and greasing your leader down to within 12 to 18 inches of the fly.

Continued – click on page link below.

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