Gray Fox - Mayfly Dry Fly
Description
While originally designed to imitate the Eastern Gray Fox, this is one of the most versatile large mayfly patterns you can carry. Its size, profile, and coloration make it an outstanding imitation of both Eastern and Western March Browns, and it's our go-to pattern here in Oregon whenever March Browns are on the water. It also makes an excellent Brown Drake imitation throughout the Great Lakes region.
Gray Foxes are found throughout much of the eastern United States and southern Canada, inhabiting medium to large rivers with rocky riffles and clean, well-oxygenated water. Traditionally considered a separate hatch from the Eastern March Brown, they are now recognized as the lighter-colored form of the same species*** Whatever you call it, this is a truly versatile pattern that covers multiple hatches and deserves a permanent place in every fly box.
The 1979 biosystematic revision by Bednarik & McCafferty, which concluded that what anglers called Gray Fox (Stenonema fuscum) and March Brown (Stenonema vicarium) are forms of the same species. That treatment has been adopted in modern taxonomy, where the valid name is Maccaffertium vicarium.
Massachusetts Trout Unlimited Hatch Guide states it very clearly:
"What was formerly M. fuscum – the Gray Fox – is now considered M. vicarium. The Gray Fox variety tends to be smaller and lighter in color than the March Brown variety"