March (Brown) madness in April and other spring flies

You see the same thing every year: on the Bitterroot, some anglers get so fixated on the skwala hatch that they forget everything else.

Never mind, especially in a year like this one, that the hatch might sputter from day to day. The angler armed with the hot new skwala fly, or a proven old one, for that matter, might find himself out of luck. These big brown-olive stoneflies bring the big fish up when they're present. And when they're not, the fish might still come up for them.

It's no wonder then, on the Bitterroot, that we see what we do every year. Either the big fish are climbing on those #8 and #10 dries, or it could be sputtery, or nothing.

Skwalas are interesting bugs. They're not like other stoneflies. The nymphs migrate to shore and try to hatch when the water's temperatures warm into the high 40s. The Catch-22 is that the sun that warms the water also melts the snow that chills and raises the water.

That makes the skwala hatch unpredictable even in the best of weather years. That's not what we've had so far. When the fish aren't keyed on skwalas they might be eating something else, if they're eating at all. Some days they aren't.

On Rock Creek, the main attraction every spring is the March Brown - a mayfly that can appear during the warm part of any sunny or high-overcast day that isn't too chilly.

I recently spoke with John at the Rock Creek Mercantile, just down Rock Creek Road from Clinton. He tells me that the March Browns on Rock Creek are just getting off to a good start and should be fully on by the time this column hits the streets. For an update, call him at 406-825-6440.

March Browns are the major spring hatch on Rock Creek. They occur just about everywhere in our area and the well-equipped angler shouldn't be without them.

They're dark brown in overall appearance, as their name suggests, and fairly large, as mayflies go. A #12 nymph/wet fly such as a pheasant-bodied soft hackle and #14 brown-bodied Sparkle Dun will get you started.

Sparkle Duns are the invention of Craig Mathews, founder of West Yellowstone's landmark shop, Blue Ribbon Flies. They can represent any number of mayflies with just a variation in size and color. Their key feature is a translucent fiber tail that simulates the shuck of a hatching mayfly.

"March Browns are notorious shuck-draggers," Justin Baker once told me. He's right - fish that March Brown with just an ever-so-slight jiggle of the rod tip to simulate the struggle of a mayfly trying to escape its nymphal shuck and it might just trigger a strike from a big trout that ignores the dead drift.

Later in the hatch, try a pattern with a slender, segmented body that lays flat on the water. My own favorite here is a takeoff on Rene Harrop's Hairwing Dun series of mayfly patterns.

March Browns have several peculiarities. Most mayflies hatch in one color and shed a thin membrane of outer skin before mating, and the females return to the stream to lay their eggs in a different color and at a different time of day. March Browns, on the other hand, look about the same before and after shedding that outer skin, and the females return to the water while the day's fresh hatch is going on. You'll see both stages - hatching bugs and egg-laying bugs - on the water at the same time.

Another peculiarity of the March Brown is that they'll hatch - or try to - underwater. They'll then swim to the surface, break free with a flurry of wings on the surface, and then - if they were successful in ridding themselves of that nymphal shuck underneath - fly off and prepare to mate.

My approach to fishing March Brown dry flies is to do this: If I see rises to those struggling shuck-draggers on the surface I'll start with a March Brown #14 Sparkle Dun, and maybe twitch it a little.

If that doesn't work, I'll switch to the slender-bodied Hairwing Dun. If I don't see many stragglers on the surface I'll start with that fly. On a day when I'm seeing occasional rises but can't tell what they're on, I might start with a double-dry rig, with that March Brown pattern behind a skwala.