Michigan Flies

Hatches / mayfly

March Brown

A

Maccaffertium vicarium (formerly Stenonema vicarium and S. fuscum)

Also called American March Brown, Gray Fox, Stenonema vicarium.

A big mottled-wing clinger that hatches sporadically from mid-May into July, late morning through evening with a mid-afternoon peak, rather than in dense flurries. Duns take a long time to get off the water in the riffles, which makes them a good target for a #10-12 parachute or Comparadun drifted through fast water and along seams. Nymphs are flat clingers on cobble; a March Brown or Hare's Ear nymph fished in the riffles before the hatch works. Ignore aggregator charts that start this hatch in March; no Michigan shop supports that.

#8–12middayafternoonnymphemergerdunspinnerpale amber-yellow to reddish-brown bodyheavily mottled tan and brown wingcream to tan body (Gray Fox form)

© Patrick Hanly · CC BY · iNaturalist · Ingham County, MI · 2021

Timing by region

  1. Southeast Lower Peninsula
    1. J
    2. F
    3. M
    4. A
    5. M
    6. J
    7. J
    8. A
    9. S
    10. O
    11. N
    12. D
    Window
    May 1 – Jul 6
    Peak
    —
  2. Southwest Lower Peninsula
    1. J
    2. F
    3. M
    4. A
    5. M
    6. J
    7. J
    8. A
    9. S
    10. O
    11. N
    12. D
    Window
    May 5 – Jul 10
    Peak
    —
  3. Northeast Lower Peninsula
    1. J
    2. F
    3. M
    4. A
    5. M
    6. J
    7. J
    8. A
    9. S
    10. O
    11. N
    12. D
    Window
    May 15 – Jul 20
    Peak
    —
  4. Northwest Lower Peninsula
    1. J
    2. F
    3. M
    4. A
    5. M
    6. J
    7. J
    8. A
    9. S
    10. O
    11. N
    12. D
    Window
    May 15 – Jul 20
    Peak
    —
  5. Upper Peninsula
    1. J
    2. F
    3. M
    4. A
    5. M
    6. J
    7. J
    8. A
    9. S
    10. O
    11. N
    12. D
    Window
    Jun 5 – Aug 10
    Peak
    —

Flies that match

Pheasant Tail Nymph (reference photo)Reference photo
Pheasant Tail Nymph
A
Nymph#10–20NaturalBeadheadFlashback

Old Au Sable Fly Shop names a #12 to #14 Pheasant Tail as the Hendrickson nymph, and it covers every Michigan Ephemerella and Baetis nymph before and during a hatch. A beadhead #10 is a standard trailer fly in U.P. steelhead rigs, and #12 to #20 versions take pink salmon in clear water. Fish it dead-drifted under an indicator or on a tight line in the weeks before each mayfly hatch.

Indicator nymphing · Euro / tight-line nymphing

Reserve · $2.75
Rusty Spinner (reference photo)Reference photo
Rusty Spinner
A
Dry fly#12–20Rusty brownRust with clear wings

Supinski's Muskegon chart says 'rusty spinners at dark' for Sulphurs, and the same fly covers Hendrickson, Cahill and March Brown falls over riffles at sunset. Fish it flush in the film at dusk from May through July when you see spent wings in the foam lines.

Dry fly

Reserve · $3.00
Adams (and Parachute Adams) (reference photo)Reference photo
Adams (and Parachute Adams)
A
Dry fly#10–20Gray (standard)Slim-bodied #10-12 for Gray Drake

Michigan's own fly, born on the Boardman, and still the default searching dry on every river in the state. Hawkins recommends a slim-tied #10 to #12 Adams for Gray Drake spinner falls at dusk on the Pere Marquette and Muskegon, and smaller sizes pass for most gray-winged mayflies from April through October.

Dry fly

Reserve · $3.00
Gold-Ribbed Hare's Ear (reference photo)Reference photo
Gold-Ribbed Hare's Ear
A
Nymph#8–18NaturalOliveBeadhead

The generalist buggy nymph for Michigan's clinger mayflies and caddis pupae, and MidCurrent lists a #10 to #14 Hare's Ear among winter steelhead nymphs. Dead-drift it under an indicator all season for trout, and as a trailer behind an egg or stonefly for steelhead.

Indicator nymphing · Euro / tight-line nymphing

Reserve · $2.75
March Brown Parachute (reference photo)Reference photo
March Brown Parachute
A
Dry fly#8–12Amber-tan (March Brown)Pale ginger (Gray Fox)

Michigan's March Brown (Maccaffertium vicarium) hatches mid May into July once water reaches the mid 50s, sporadically through the afternoon rather than in a blizzard. The same species appears as the paler Gray Fox, so carry both shades in #10 to #12. Strongest on the Upper Manistee, Muskegon and Chocolay.

Dry fly

Reserve · $3.00