March Brown

Other Common Names: Western March brown
Scientific Names: Rhithrogena morrisoni, R. hageni

On many rivers, the March browns are the first large mayflies of the new year. After a winter of tiny blue-winged olives and even tinier midges--always fussy and unpredictable hatches--the March browns are the heralds of all the delights of the next eight months.

In Oregon's Willamette Valley they usually start about the first week of March, although they can be earlier or later depending on the warmth of the weather. On the Willamette, McKenzie, and other Oregon rivers, March browns are beloved by local anglers even though the bugs often hatch in godawful weather. Many ardent fly fishers will spend a March afternoon shivering in a driftboat as droplets of cold rain run down the sleeve of their casting arm. If you listen close, you can hear them mummering, "It just doesn't get any better than this."

Members of the clinger group of mayflies (family Heptageniidae), March brown nymphs live in riffles and fast, rocky runs. Nymphs are so well adapted to their habitat that they are seldom found in the drift until emergence time. As the nymphs near maturity, they migrate to slower (but not slow) water, usually within a hundred yards above or below a riffle.

Hatches usually start in the early afternoon. Just prior to the hatch, nymphs are often found drifting in the current, so it makes sense to present a nymph pattern near the bottom beginning a couple of hours before the hatch. As the nymphs hatch, they often drift a long distance before reaching the surface, so you find drifting nymphs anywhere from just below a riffle to runs that are well below them.

Duns usually emerge on the surface. As trout switch their focus to the duns and you see surface rises, change to a dry fly. Sometimes, however, emergence happens underwater and the dun floats to the surface. In this case a Soft Hackle or downwing wet fly works best.

Spinners return to lay eggs over the riffles, but they usually do so sporadically and rarely in a concentration that captures the interest of trout.

Characteristics

NYMPH COLOR: Dark brown, sometimes olive-brown

DUN SIZE: 8-15 mm (5/16 to 5/8 in)

DUN COLOR: Wings--mottled brown and tan. Body--brown on top, tan below.

OTHER CHARACTERISTICS: Nymph--gills overlap under the abdomen; flattened appearance; three-tailed; head is wider than the abdomen. Dun--two tails.

Click on the fly name to see the pattern. Click on the presentation to learn how to do it.

STAGE PATTERN SIZE/
COLOR
PRESENTATION WHERE
Nymph Hares Ear 10-14
Brown
indicator, tight line, rising nymph Near riffles
Pheasant Tail 10-14
Brown
indicator, tight line, rising nymph Near riffles
Emerger Soft Hackle 10-14
Brown
surface swing Near riffles, flats
Quigley Cripple 10-14
Tan to red-brown body, brown wing
standard dry fly Near riffles, flats
Film Critic 10-14
Tan to red-brown body, brown wing
standard dry fly Near riffles, flats
Hackle Stacker 10-14
Tan to red-brown body, brown wing
standard dry fly Near riffles, flats
Dun Sparkle Dun 10-14
Tan to red-brown body, brown wing
standard dry fly Near riffles, flats
Hairwing Dun 10-14
Tan to red-brown body, brown wing
standard dry fly Near riffles, flats
Comparadun 10-14
Tan to red-brown body, brown wing
standard dry fly Near riffles, flats