Hatch profile
Ephemerella subvaria
Water-temperature trigger
Top fly patterns
First substantial mayfly hatch on most Eastern rivers. Spinner falls in evening can be as productive as the dun emergence.
Best rivers
Pennsylvania
Brodhead Creek
Apr 25 – May 15 · heavy
Pennsylvania
Big Fishing Creek
Apr 25 – May 15 · heavy
Pennsylvania
Loyalsock Creek
Apr 25 – May 15 · heavy
New York
Beaverkill River
Apr 25 – May 20 · heavy
New York
Willowemoc Creek
Apr 25 – May 20 · heavy
New York
Esopus Creek
Apr 25 – May 20 · heavy
New York
Neversink River
Apr 25 – May 20 · heavy
New York
Rondout Creek
Apr 25 – May 20 · heavy
Virginia
Rapidan River
Apr 25 – May 15 · moderate
Virginia
Rose River
Apr 25 – May 15 · moderate
West Virginia
Cranberry River
Apr 25 – May 15 · moderate
West Virginia
Elk River (headwaters)
Apr 25 – May 15 · moderate
West Virginia
Shavers Fork
Apr 25 – May 15 · moderate
West Virginia
North Fork South Branch Potomac
Apr 25 – May 15 · heavy
Maryland
Big Gunpowder Falls (freestone upper)
Apr 25 – May 15 · heavy
New Jersey
South Branch Raritan River
Apr 15 – May 5 · moderate
New Jersey
Musconetcong River
Apr 25 – May 15 · heavy
Connecticut
Farmington River
May 1 – May 25 · heavy
Connecticut
Housatonic River
May 5 – May 25 · heavy
Vermont
Battenkill River
May 5 – May 25 · heavy
Vermont
Lamoille River
May 15 – Jun 5 · heavy
New Hampshire
Upper Connecticut River
May 15 – Jun 5 · heavy
Maine
Kennebago River
May 15 – Jun 5 · heavy
Maine
Rapid River
May 15 – Jun 5 · heavy
Other rivers with Hendrickson activity
Bield Fish watches USGS water-temp gauges for your home water and pings you when conditions hit the 50–58°F trigger window.
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