March browns (Stenonema vicarium) are among the more important hatches in the East and the Midwest. The big bugs don’t usually create blanket hatches, but instead emerge sporadically throughout the day, which means you can often get a trout to eat a dun even when there aren’t any bugs actually on the water.
In this great video from Tightline Productions, Matt Grobert (an author and blogger) demonstrates the traditional Catskills method for tying this pattern.Catskills tiers were notoriously picky about keeping flies fairly sparse, with all the parts in correct proportions, and with some bare shank behind the hook eye. Grobert offers a great primer on creating hackle wings that are well separated, stand up nicely, and look great.
March Brown Dry
Hook: Standard dry-fly hook (here a Mustad 94840), sizes 10-14.
Thread: Olive, 6/0 or 140 denier.
Wing: Wood-duck feather.
Tail: Brown hackle fibers.
Body: Fawn-colored rabbit-fur dubbing.
Hackle: Brown and grizzly hackle.
Head: Tying thread.