When it comes to the names of trout bugs, two mayflies stand out: pale-morning duns and blue-winged olives.
Pale-morning duns is so lyrical the name was stolen for the titles of at least two works of fiction. Since I’m a fly fisherman fiction is really just a fine old friend. I’ll have to write my own novel about a famous artisanal muffaletta maker who gives up a profitable gig on the Food Network so he can embark on a quest to find the perfect olive to dress his sandwiches.
Blue-winged olives are smallish mayflies that take their name from their smoky, blue-gray colored wings and green bodies. They’re an off-season spring-fall hatch in most of the Northern Rockies. I hear of olive hatches on cloudy days in the summer, but with bigger, more numerous bugs usually on the water that time of year, olives are rarely the focus.
I was floating the South Fork Flathead River last summer below Hungry Horse Dam with my pal Funkmaster Fred when a rainstorm broke out. I rowed while Funkmaster fruitlessly sank big nymphs in hopes of dredging up a nice fish. We stopped to make sure we had time to consume our allotment of beer before we reached the take out, and while eddied out behind a large boulder I noticed rises. Between the raindrops, trout were sipping something off the surface.
In the current seam I saw the wings of mayflies. They looked like tiny sailboats. I can’t be sure they were blue-winged olives, but the bugs were small, grayish-looking and it was cloudy. At my urging Funkmaster tied on an Adams and picked up a couple hits and boated a small cutthroat while we waited out the storm. But then we were out of beer so we hustled to the take out.
Olive hatches disappear during the hardest months of winter. That’s where dams come in. I despise dams every bit as much as the next Edward Abbey fan, but that doesn’t mean I avoid fishing below them as some misguided statement of principle. Dams create tailwaters, which often means trout fishing where none previously existed.
There would still be trout in the South Fork without the dam. But in Arizona, Glen Canyon Dam transformed the Colorado River from a warm, muddy flow so silty it almost seemed plowable into a world famous trout fishery at Lees Ferry. The water below Glen Canyon is so cold when biologists introduced mayflies the bugs couldn’t survive.
Dams make rivers colder in summer and usually have the opposite effect in winter. Where freestone streams are in the grips of anchor ice, in nearby tailwaters the bugs, and trout, often remain lively.
And so it was on a fine December afternoon just before Christmas when I fished a Wyoming trout stream that flows off the eastern edge of the Yellowstone Plateau into a reservoir that stores spring melt so it can be used to grow sugar beets in August. It was 37 degrees when I pulled up to the river and trout were rising. I saw one come six inches out of the water chasing some unseen bug. I tried a pair of emerger patterns, but I was on the shady side of the canyon and the action was out in the sun. I made a few reckless casts across river, but the fish probably sensed my fly dragging before it hit the water.
I moved on to a spot where I could see fish working in the slow current near the tail of a long run, but the rises were whitefish. I watched a little longer and then saw little gray sailboats floating in the current. I tied on a hi-vis Adams and went to work.
I caught five fish, a mix of trout and whitefish including one chubby cutthroat that might have pushed 14 inches. I never measure fish. It’s a scientific fact that contact with a tape measure causes trout to shrink by a couple of inches.
And there’s this blue-winged olive truth to consider: Any trout caught on a dry fly in the dead of winter is a trophy, no matter the size.