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Hendrickson (Ephemerella subvaria)
Mayfly, hatching April, active in water between 45 and 58°F, and imitated at #12–14. Recorded from southeast Minnesota, where 99 Minnesota rivers on this site carry a page.
- #12–14Hook size
- 45–58°FWater, active
- AprPeak months
- 4Life stages fished
What it is
Mayfly · Ephemerella subvaria · nymph → emerger → dun → spinner
A medium mayfly with a pinkish-tan body and slate-grey wings that stand upright over the water like small sails. The female is noticeably paler and larger than the male, which is dark enough that anglers once treated the two as separate hatches — the Hendrickson and the Red Quill.
The first hatch of the year worth planning a trip around. Comes off early afternoon, when the water is warmest.
When it hatches
These are Minnesota's own dates, not this site's shared calendar. They are the Dark Hendrickson (Ephemerella subvaria) row of Hatch Chart for Southeast Minnesota Trout Streams, Minnesota Department of Natural Resources, Lanesboro Area Fisheries (Vaughn Snook, Assistant Fisheries Supervisor), as of 15 June 2016. The chart's calendar runs January to October and makes no claim about November or December. Its own footer says it is a general time frame, that some streams have only a few of these hatches, and that others may see hatches it does not list.
Peak is April. 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 45°F to 58°F. On this map that is cold, cold-transitional water — the band crosses 1 of the three break 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 stout, three-tailed crawler that clings to gravel and cobble in moderate current. It is available all winter, and a dark hare's-ear or pheasant-tail fished on the bottom is a Hendrickson nymph whether anyone calls it one or not. |
| emerger | Emergence happens in the film, and it is slow: the dun struggles out of the nymphal shuck at the surface and drifts. Trout key on this stage hard enough that a floating dun over feeding fish is frequently refused while a film pattern is not. |
| dun | Upright grey wings, tan-pink body, riding the surface for several yards before flying. This is the stage the hatch is named for and the one worth planning an afternoon around. |
| spinner | The mated female returns in the evening with clear wings held flat on the water. Bodies darken to rust-brown, which is why a Red Quill Spinner covers the fall and a dun pattern does not. |
Matching flies
5 patterns in this book imitate the Hendrickson, 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.
- Hare's Ear Nymph nymph · #10–18 — Looks like everything and nothing. The other half of a two-nymph rig.
- Hendrickson Dun dry fly · #12–14 — Pink-grey body, dun hackle. Matched to the real thing when a general pattern gets refused.
- Parachute Adams dry fly · #12–20 — Universal mayfly dun imitation. Every angler carries these.
- Pheasant Tail Nymph nymph · #12–22 — The mayfly nymph. Beadhead or not, size 16, and half the trout in the world have eaten one.
- Red Quill Spinner dry fly · #12–16 — The Hendrickson male, and the evening fall after the hatch.
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.
- Badger Creek southeast Minnesota
- Bear Creek southeast Minnesota
- Bear Creek southeast Minnesota
- Beaver Creek southeast Minnesota
- Beaver Creek southeast Minnesota
- Beaver Creek East southeast Minnesota
- Beaver Creek West southeast Minnesota
- Bee Creek southeast Minnesota
- Big Springs Creek southeast Minnesota
- Big Trout Creek southeast Minnesota
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.
- northern lower Michigan MI
- southern lower Michigan MI
- the Upper Peninsula MI
- the Wisconsin driftless WI
- northern Wisconsin WI
- the Virginia mountains VA
- the North Carolina mountains NC
- southeast Minnesota MN
Rivers in these regions with a page here
- Badger Creek
- Bear Creek
- Bear Creek
- Beaver Creek
- Beaver Creek
- Beaver Creek East
- Beaver Creek West
- Bee Creek
- Belle Creek
- Big Springs Creek
- Big Trout Creek
- Bridge Creek
- Butterfield Creek
- Camp Creek
- Campbell Creek
- Canfield Creek
- Carson Creek
- Cedar Creek
- Clear Creek
- Cold Creek
- Corey Creek
- Crooked Creek
- Crow Spring
- Crystal Creek
- and 75 more
Related hatches
Same family, or overlapping this one's calendar on the same water.
- Blue-Winged Olive Baetis spp. · Mayfly · March–May and September–November
- Blue Quill Paraleptophlebia adoptiva · Mayfly · April–May
- Light Cahill Maccaffertium ithaca · Mayfly · May–July
- Sulphur Ephemerella invaria · Mayfly · May–July
- Little Sulphur Ephemerella dorothea · Mayfly · May–July