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American March Brown
Pattern Image:
General Description:
The American March brown, at size 10 to 12, is the largest mayfly at the point of the season when it begins to emerge. Hatches last from mid-May until mid-July. On any given water, it lasts about two weeks, then trickles on for another week or two. The nymphs are most abundant in freestone streams, and live in fast water, but migrate to margins and pools to emerge. Duns come off in late afternoon and early evening, though in unseasonal warm weather it can be a morning hatch. Spinner falls do not happen every day, but on evenings when they do fall, it's in great numbers, and trout feed selectively on them. You should carry dressings for the nymph, the most important dun, and the occasionally-important spinner.
Stage Description:
The American March brown dun is large, showy on the water, and though there are not always a lot of them, they attract the attention of trout. Their bodies are creamish-tan on the all-important underside that trout see. Their wings are pale tan to tannish-yellow, mottled brown. As the hatch progresses the insects become smaller and lighter in color, giving rise to the thought that they were more than one species. They are not, but watch their size and color, and change your imitation if necessary. It's common for the duns to struggle and make false starts before launching. The hatch is more often trickling than heavy, but it keeps trout up and interested. Use a hackled pattern so you can twitch and skate it if a dead drift fails to work.
Hook:
Standard dry fly, size 10-14.
Thread:
Orange 6/0 or 8/0.
Tail:
Ginger hackle fibers.
Body:
Tan dubbing.
Hackle:
Grizzly and ginger, mixed.
Category:
Trout Flies: Imitators
Insect Family:
Mayflies
Insect:
American March brown (Maccaffertium vicarium syn Stenonema vicarium)
Stage:
Dun
Pattern Name:
American March Brown
Wing:
Wood duck flank.
