Michigan Flies

Hatches / mayfly

Sulphur

A

Ephemerella invaria (= E. rotunda)

Also called Sulphur Dun, Big Sulphur, Pale Evening Dun (older usage), Ephemerella rotunda.

The second of the Au Sable's Big Five and the bread-and-butter afternoon hatch of late May and June on the northern rivers, with dense hatches on the Pere Marquette that create selective risers in slow glides and tail-outs. Emergence is sporadic through the day with an afternoon-to-evening peak, and spinners drop at sunset. Trout routinely refuse duns during this hatch, so emergers and rusty spinners outfish dun patterns; carry pale yellow, orange and olive shades because body color varies. On the Muskegon and Pere Marquette the hatch runs a size smaller and continues through July.

#12–16middayafternoondusknymphemergerdunspinnerpale yellow to yellow-orange bodyyellowish-olive body (some populations)pale gray wingrusty brown spinner

© Mark Richman · CC BY · iNaturalist · Sugarland Run, VA · 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 – Jun 24
    Peak
    May 24 – Jun 16
  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 – Jun 28
    Peak
    May 28 – Jun 20
  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 8
    Peak
    Jun 7 – Jun 30
  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 8
    Peak
    Jun 7 – Jun 30
  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 – Jul 29
    Peak
    Jun 28 – Jul 21
  6. Muskegon River below Croton Damlocal chart
    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 – Jun 30
    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
Sulphur Emerger (reference photo)Reference photo
Sulphur Emerger
A
Emerger#14–20Yellow-orange with brown Z-Lon shuckCreamy yellow with pheasant tail shuck

Michigan Sulphurs emerge slowly through the film and trout often refuse duns, so emergers with a trailing shuck outfish the dry from mid May through July on the Au Sable, Pere Marquette and Muskegon. Fish it low in the film during the afternoon and evening emergence in 52 to 60 F water; size #16 for invaria and #18 to #20 for dorothea.

Dry fly

Reserve · $3.00
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
Roberts Yellow Drake
A
Dry fly#4–18Yellow (deer-hair body)Yellow tied large for Hex

Grayling's all-purpose pale mayfly, an extended deer-hair body under a parachute post, sized #4 through #18 to cover Sulphurs, Cahills, Brown Drakes and the Hex. Hawkins names a large Roberts Yellow Drake as a Hex dun and spinner; fish it after dark in late June on a short 6 ft 2X leader. Every Au Sable shop stocks it.

Dry fly

Reserve · $3.00
Sulphur Comparadun (reference photo)Reference photo
Sulphur Comparadun
I
Dry fly#14–20Pale yellowYellow-oliveYellow-orange

A low-riding no-hackle dun for the Sulphur hatch that runs mid May into July on Michigan rivers, with an afternoon emergence window of one to two hours. Carry creamy yellow through olive and orange shades to match the Au Sable's variable naturals, in #14 to #16 for E. invaria and #18 to #20 for E. dorothea. Switch to an emerger or rusty spinner when fish refuse it.

Dry fly

Reserve · $3.00
Soft-Hackle Wet Fly (reference photo)Reference photo
Soft-Hackle Wet Fly
A
Wet fly#8–16Partridge and orangePartridge and greenHare's ear soft hackle

Perfect Fly lists wet flies among St. Marys Atlantic salmon patterns, and Atlantics feed on caddis and midges from mid July through August. A swung soft hackle covers emerging caddis pupae and Sulphurs on any Michigan river; swing it down and across in riffles at dusk, or hang it below a dry.

Swinging flies (spey / switch) · Dry fly · Indicator nymphing

Reserve · $2.75
Yellow Crane Fly Adult
A
Dry fly#14–16Pale yellow with long legs

Supinski's Muskegon chart notes #16 yellow crane flies hatching along with the Sulphurs in late May and June, often confused with mayflies by anglers. Skate or dead-drift a long-legged yellow adult in the evening when fish refuse Sulphur duns on the Muskegon.

Dry fly

Reserve · $3.00