Missoula, Montana Fly Fishing
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Pale Evening Dun

Photo by Les Korcala

Pale Evening Dun Overview

  • Family: Mayfly
  • Size: 5-8mm (Size 16-18)
  • Emergence:  Early July through August
  • Emergence Time:  7:30 Pm – Dark

The Pale Evening Dun hatch in Montana is a sneaky hatch. PED’s emerge from late June through August on the Blackfoot River, Bitterroot River, Rock Creek and the Clark Fork River around Missoula.

As the name implies, they come off at night, making it perfect for the after-work angler. However, the PED emergence is extremely weather dependent. On a cool, cloudy day the PED’s may start hatching as early as 7:30 pm, but on those hot, cloudless days when the temperatures soar, it may not hatch until 10 minutes before dark. So you have to be weather aware and be on the water when the insects are moving.

Fly Fishing The Pale Evening Dun Hatch

On hot days, the angler needs to prepare for a rapid burst of action right before dark. When you’re on the water, waiting for the hatch, drop down one tippet size but add a little length. Make sure your knots are good and tight, and then get ready. Heavier tippet means you have less chance of breaking your fly off, and then trying to tie a new fly on in the dark. The additional length allows the fly to float more naturally. Carry two flashlights. One might be a head lamp, for changing flies or using a desiccant. A large flashlight will help you get off the water in the pitch black!

When you’re fishing after dinner, make sure you plan to be on the water until dark. There’s no need to rush to the water directly after work. Take your time, and make sure you’re out late enough to find the PED’s. If you do get out early, be ready for the Golden Stones and Yellow Sallies.

PED’s are a size 16 or 18, and can be imitated with the same flies you use for the Pale Morning Duns, again in different sizes. The PED’s can be very prolific, so again have emerges, adults and cripples. Watch the rise form, and make sure the fish are coming all the way to the surface. Most annoyingly, when the first strong chill of the evening hits, you’ll sometimes notice the rise forms have changed again. There are many evenings that trout will stop rising at that first chill, only to be replaced by Northern Pike Minnows and Whitefish. If all of a sudden you’re taking small non-trout, it might be time to head for home! The trout aren’t coming back. 

Additional Pale Evening Dun Resources