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Pale Morning Dun (Ephemerella excrucians)
Mayfly, hatching June–July, active in water between 50 and 65°F, and imitated at #14–18. Recorded from the Wisconsin driftless and northern Wisconsin, where 1611 Wisconsin rivers on this site carry a page.
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A pale yellow-olive mayfly, size 14 to 18, emerging through the warm middle of the day in early summer, with the peak in June and July. Bodies vary from cream to distinctly olive between rivers, so a single shade of dubbing is not a safe assumption. The nymph is a small olive-brown crawler in weed and gravel. The film stage is where the fish are, and emergers are refused less often than duns on flat water; the dun itself is pale yellow with light grey wings, size 16 either side, and rusty spinner falls come morning and evening both. Activity spans 50 to 65 degrees, covering cold, cold-transitional and cool water, and it is strongest on driftless spring creeks where water temperature barely moves. Frenchie 12 to 18 and Pheasant Tail 12 to 22 below; PMD Sparkle Dun 14 to 18, Sulphur Dun 14 to 18, Sulphur Comparadun 14 to 20, RS2 16 to 24, Rusty Spinner 14 to 20 above.
- #14–18Hook size
- 50–65°FWater, active
- Jun–JulPeak months
- 4Life stages fished
What it is
Mayfly · Ephemerella excrucians · nymph → emerger → dun → spinner
A pale yellow-olive mayfly, size 14 to 18, emerging through the warm middle of the day in early summer. Bodies vary from cream to distinctly olive between rivers.
Morning and midday. Strongest on the driftless spring creeks, where water temperature barely moves.
When it hatches
Peak is June–July. The pale months either side are the shoulder — the app widens a peak by one month in each direction and recommends the bug there, and no further: that widening is bounded so that a bug peaking in May is never offered in August.
peak shoulder not recommended
Water conditions
The band is a water temperature, not an air temperature, and it is the range in which this insect is worth fishing — for a mayfly that is the emergence window; for a scud or a midge it is simply the range trout will still eat one in.
Active from 50°F to 65°F. On this map that is cold, cold-transitional, cool water — the band crosses 2 of the three breaks the river colours use. Breaks at 58, 64 and 70°F.
Stages
What the insect is doing, and what that means for what you tie on.
| Stage | What it is |
|---|---|
| nymph | A small olive-brown crawler in weed and gravel. |
| emerger | The film stage is where the fish are, and PMD emergers are refused less often than PMD duns on flat water. |
| dun | Pale yellow body, light grey wings, size 16 either side. |
| spinner | Rusty spinner falls, morning and evening both. |
Matching flies
7 patterns in this book imitate the Pale Morning Dun, across its stages. Which one to tie on follows the stage the water temperature says it is in — the app makes that call on a live reading; this page lists the whole set.
- Frenchie nymph · #12–18 — A Pheasant Tail with a hot spot. The most-fished competition nymph there is.
- Pheasant Tail Nymph nymph · #12–22 — The mayfly nymph. Beadhead or not, size 16, and half the trout in the world have eaten one.
- PMD Sparkle Dun dry fly · #14–18 — Morning fly on spring creeks. Trailing shuck does most of the work.
- RS2 emerger · #16–24 — The emerger that saves a hatch you cannot otherwise crack. Fish it in the film.
- Rusty Spinner dry fly · #14–20 — Almost every mayfly spinner is rust-coloured. This covers the last hour of light.
- Sulphur Comparadun emerger · #14–20 — No hackle, sits in the film. What to tie on when duns are drifting past untouched.
- Sulphur Dun dry fly · #14–18 — Pale yellow-orange. Evening hatch fly on nearly every eastern river.
Where to find it right now
The rivers with a page here that sit in this insect's regions, with a USGS gauge reporting water temperature. This list is re-ranked against the reading each gauge is sending now and today's date, so it is live — the fallback below it, if the readings do not arrive, is each river's measured July mean.
- Black Earth Creek the Wisconsin driftless · July mean 61.6°F
- Baraboo River the Wisconsin driftless · July mean 62.2°F
- Billings Creek the Wisconsin driftless · July mean 62.2°F
- Brandy Creek the Wisconsin driftless · July mean 62.2°F
- Brewer Creek the Wisconsin driftless · July mean 62.2°F
- Cazenovia Branch the Wisconsin driftless · July mean 62.2°F
- Council Creek the Wisconsin driftless · July mean 62.2°F
- Deer Creek the Wisconsin driftless · July mean 62.2°F
- Fountain Creek the Wisconsin driftless · July mean 62.2°F
- Grinsell Branch the Wisconsin driftless · July mean 62.2°F
Regional presence
Regions, not collection records. This insect is recorded from the coarse regions below; nobody has surveyed which named river it has been caught on, and this page will not pretend otherwise.
- the Wisconsin driftless WI
- northern Wisconsin WI
- the Upper Peninsula MI
Rivers in these regions with a page here
- Saint Croix River
- Adams Creek
- Alder Creek
- Alder Creek
- Allen Creek
- Allen Creek
- Allen Creek
- Allen Creek
- Allenton Creek
- Allequash Creek
- Alvin Creek
- Amo Creek
- Anderson Creek
- Annis Creek
- Apple Branch
- Apple Creek
- Apple River
- Arkansaw Creek
- Armstrong Creek
- Armstrong Creek
- Arnold Creek
- Ash Creek
- Auburn Lake Creek
- Augustine Creek
- and 1587 more
Related hatches
Same family, or overlapping this one's calendar on the same water.
- Hex Hexagenia limbata · Mayfly · June–July
- Isonychia / Slate Drake Isonychia bicolor · Mayfly · June–September
- Light Cahill Maccaffertium ithaca · Mayfly · May–July
- Little Yellow May Leucrocuta / Heptagenia spp. · Mayfly · June–September
- Sulphur Ephemerella invaria · Mayfly · May–July