Hey ya'll, welcome to Match the Hatch! For March's Match The Hatch we're going to be talking about March Browns!
March browns are an exciting hatch because they are the first 'big bug' hatch of the year. Their arrival marks the coming of spring and more importantly, the start of trout season! Those of us fishing in the winter months finally get to enjoy wearing some less layers and all of us get to enjoy some longer hatch windows due to the warming weather.
Rhithrogena morrisoni, commonly known as a March Brown, have body colors that range from a tan or pale brown to a reddish brown, a mottled wing, and two tails. The season for March Browns is generally late spring from mid-April through early June. Duns emerge during mid-morning hours. Spinners fall in the evenings. If we have a warm spring this year you can easily see them in mid-March, especially on waters like the McKenzie River.
Their emergence begins when water temperatures rise to about 47 or 48 degrees. When water temp hits 50 degrees the emergence will be in full swing. Hatches can vary widely from one day to the next, it just depends on weather conditions. Mild stable weather with overcast skies generally produces large hatches. Due to their spring emergence, spring run off and high water levels can often ruin a day's fishing and blow out a river. Keeping notes on ideal river levels for your favorite streams is recommended so you can tell at a glance if it's worth visiting or not.
Because they are a clinger type of mayfly, March Browns prefer riffles and glides with baseball to bowling ball sized substrate in moderate to large rivers throughout the West. With March Browns being found in and below riffles, they are a great mayfly for swinging soft hackles, which is my preferred method next to sight casting for risers. If river regulations allow the use of multiple flies; a dry dropper or a brace of soft hackles would be my recommendation. Just keep those casting loops wide to prevent tangles and knots in your tippet and leader.
Flies for March Browns are usually size 12-14. Some useful nymphs are Pheasant Tails, Pheasant Tail Soft Hackles, March Brown Emergers, Hare's Ears, and I'd definitely recommend swinging some March Brown wet flies. A few of my favorite dries to use are Quigley Cripples, Sparkle Duns, Parachute March Browns, and be sure to include some spinners too for the evenings and early morning back eddies.
Colby Olson
Fly Fishing Guide