Pale Evening Duns

By Mike Schoby

In many Western rivers, pale evening duns are one of the strongest mayfly hatches. Hatches can begin in late spring and continue through much of the summer.

Inhabiting areas with moderate to fast current, the nymphs seldom loose their grip on the rocky bottom prior to the hatch season. However, nymphs are often taken as they rise to the surface during a hatch, and the emerger, dun, and spinner stages are all important.

Nymphs During Emergence

Nymphs migrate to slower water when they are mature, so hatches generally happen in the margins and in backeddies. During a hatch, nymphs rise quickly to the surface. Trout take them on the rise, and this is really the first major opportunity for fly fishers.

If it is early in the afternoon and there is no hatch coming off, rig up a beadhead Hares Ear , Pheasant Tail , or similar nymph with a strike indicator. You'll need to collect a sample nymph to match the size because they can range from size 12 to 16. Dead-drift your fly along the bottom, concentrating on the slow water on the sides of the main runs and in the margins.

In slow water, trout are especially wary. So if you're having trouble picking up fish that you suspect are feeding on nymphs, try a downstream presentation and no indicator.

Just before a hatch or in the hatch's early stages, use a non-weighted nymph and no indicator. Quarter your casts downstream, and at the end of the drift allow the fly to swing upwards in the water column, imitating a rising nymph. At the end of the swing let it hover in the current, giving it an occasional small twitch. A Soft Hackle can work very well when presented in this manner.

Dry Flies During Emergence

There are a multitude of suitable mayfly patterns to choose from. Some of my favorites are Light Cahills and Quigley Cripples . Sparkle Duns , Comparaduns , and Parachute Hares Ears are other good choices.

Because of variations in size, you'll probably need to collect a sample from the area you're fishing, then match its color and size. Remember: if you just look at a flying bug and don't collect and measure it, you will probably choose a fly that is one size too big.

If there are numerous other insects on the water, it is unlikely a trout is going to move more than a couple of inches to swallow your offering. So present your fly accurately. You'll probably need a downstream presentation due to the slow water these insects usually hatch in.

I find that emerger patterns generally out-fish dun imitations by a large margin. They should be tied and dressed so they ride low in the water with only the thorax in the film. Emerger patterns (see above) will be one of the most effective flies in your box.

Often it will be to your advantage to fish two flies. Use a high-riding dry with a 12-18 inch dropper off the hook bend. Put an emerger pattern on the dropper. The dry fly now does double duty as a strike indicator. This works well late in the evening when the light is low because the dun will be a lot easier to see in the diminished light. Strike at any rise or disturbance around the dun; more often then not there will be a fish at the other end.

Spinner Stage

After two days, duns molt into spinners and mating takes place. Mating flights occur anytime from mid-afternoon to dusk, and spinner falls can overlap with hatches. A Polywing Spinner with a tan-yellow body is the right choice.

Some of the best spinner fishing is in backeddies, where the current collects the spent mayflies and offers trout more morsals for their efforts.

Since spinner falls and hatches can occur at the same time, and since it can difficult to tell which stage the trout are rising to, it pays to double up. Use the dropper technique described above, only tie on a spinner pattern instead of an emerger or nymph.