Fall was slow to cool down to the temperatures that bring gray skies, cold rain, the beginnings of snow, jackets, hats, and hatches of Baetis mayflies, but finally summer has vanished and the little Blue-Winged Olives are emerging in quantity. These small greenish mayflies challenge both our eyes and our skills, because you have to present an itty-bitty imitation to trout that won’t move far to eat. For BWOs, one fly pattern always traveling in my fly box is the Comparadun, a dry fly/emerger with a fan-shaped wing of fine deer hair that floats the fly low in the film. On a scale of 1 to 10, for both effectiveness and ease of tying, it scores a perfect 10.
Begin with a size 16 or 18 standard dry-fly hook. Attach a fine brown thread to the rear of the hook just in front of the bend, leaving a tag of two inches or more of thread sticking out behind the bend. This thread will be used later to split the tails. Wrap the thread three-quarters of the way up the shank to the front of the thorax area and pause. Select two to six dun Microfibbets or hackle barbs and tie these in along the top of the shank at the thorax area, butts forward, so the tapering tips extend back beyond the bend about the length of the shank, then wrap back over them, stopping at the bend, and trim any excess butt material. Now take the thread tag dangling off the back and pull it forward, splitting the tail fibers into equal halves. Wrap the thread up the length of the tag, ending it at the thorax. Next, select some fine dun or natural-colored deer hair, trim it away from the hide, and even the tips in a hair stacker. Tie it down where the underbody ends, tips forward, so that it fans out, the same length as the hook shank. Cut off the hair butts close to the shank, bind them down, and wind the thread forward in front of the fanned deer hair. Wrap back against the front of the wing, propping the
hair straight up. Then wrap back to the hook bend, sparsely apply some olive dubbing to the thread, wrap forward to the eye, and tie off. You are finished. The body should be tapered, thickest at the thorax wing area.
This pattern has fooled many fish for me, from the Sacramento to Yellowstone. In fact, my fondest Baetis experience occurred on the steamy Firehole. It had been sunny earlier in the morning, but now the gray sky above me threatened rain or snow. Despite shivering in my waders, I was enjoying a prolific Baetis hatch. Rainbows 8 to 14 inches long were methodically rising, gently sipping the tiny olive sailboats. I was knee-deep in the river, recovering from the excitement of watching a gargantuan brown trout swirling around a panicked rainbow stuck to my fly. That brown and I, for a split second, saw eye to eye, and just as quickly the giant disappeared. More and more mayflies fought their way through the surface film. Fish were everywhere. All you saw of their presence was a gentle surface disturbance as mayflies vanished. I focused on a rise about midstream, 30 feet or so up current. The cast was perfect, drifting down the feeding lane. No grab. I cast again, cast again . . . nothing. I waded closer. Cast. Nothing. Crouching, I waded within 15 feet, not daring to sneak any nearer. The fish kept rising. What the hell? My casts were perfect. Finally, I got within 10 feet in bewildered frustration. I kept watching that methodical, steady rise. Finally, I walked right up to the fish. But it wasn’t a fish — it was thermal gas, rhythmically rising from fissures in the river bottom. I was duped by a fumarole. There was laughter behind me. I was fishing with what I thought was a friend.
— Andy Guibord
