March is finally here and for the fly fisher it’s probably the first major hatch of the season. Are you ready for March Brown mayflies to begin hatching on your local river?
For me, this is the first hatch I really look forward to. Give me a Sparkle Dun March Brown and Pheasant Tail Soft Hackle and point me to the river!
I’ve seen a few memorable hatches.
The first was drifting the McKenzie River outside of Eugene many years ago when I lived in the Willamette Valley and observed nymphs swimming to the surface, pausing briefly while the dun broke free of the nymphal shuck and flew away. It happened so fast, I didn’t have time to reach down and grab one to get a closer look. I’m guessing that’s why trout rise so quickly and with purpose. They don’t want the dun to get away.
The other great hatch I witnessed was on the Middle Deschutes River. I’ll call it April Browns because the irrigation ditches are opened in mid-April which lowers the water level in the river to a very fishable level. That’s the time I hit the river. I remember catching so many Browns and Rainbows on a March Brown Comparadun that I barely had any deer hair remaining for the wing. The few fibers with dubbing remaining on the hook still was enough to catch more trout!
This is the first of the larger mayflies trout will see in the coming months and an emerger or dry fly is a lot of fun to fish.
As a reminder, here is their typical life-cycle.
Western March Brown mayflies (Rhithrogena morrisoni) are in the #12 – 16 size range. If you look at them from above, they appear a medium to dark brown. But that’s not what the fish see. The fly’s abdomen where I live is a reddish-brown, but they might be different in the waters you fish. And their wings are very distinct…brown and mottled or some fly fishers would call it cathedral window-like.
Like all aquatic insects, it begins with an egg. The egg hatches and becomes a small nymph, living in fast, clean water. The March Brown nymph is known as a clinger because it attaches itself to the bottom of the river by it’s gills, which act like suction cups. Meals consist of algae scraped off the rocks where the nymph lives and grows.
After living and growing in the river for about a year, it’s time to hatch. The nymph swims to the surface and escapes the nymphal shuck and the adult, or dun as their known, flies away.
The dun lives along trees and brush waiting as it sexually matures, molting again into the spinner phase. After mating and laying eggs, spinners fall into the water where they are available for the trout to feed upon them.
If you would like to get more information about March Browns or any other aquatic insect, I highly recommend the book BugWater by Arlen Thomason. It’s a favorite of mine. Another great resource is Western Mayfly Hatches: From the Rockies to the Pacific by Rick Haefle and Dave Hughes. Go to your local fly shop and see if they carry it or click on the Amazon link.
Here are the other dry flies you’ll see in my fly box.
I taught a Zoom fly tying session demonstrating a couple of the imitations I like.
Nymph, emergers, and adults are all important to the fly fisher. I’ve shared the emergers, so here are effective nymphs and dry flies.
What are your favorite imitations?
Enjoy…go fish!
