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Hendricksons

Like most common names, "Hendrickson" can refer to more than one taxon. They're previewed below, along with 8 specimens. For more detail click through to the scientific names.

Mayfly Species Ephemerella subvaria

These are pretty much always called Hendricksons.
The Hendrickson hatch is almost synonymous with fly fishing in America. It has been romanticized by our finest writers, enshrined on an untouchable pedestal next to Theodore Gordon, bamboo, and the Beaverkill.

The fame is well-deserved. Ephemerella subvaria is a prolific species which drives trout to gorge themselves. Its subtleties demand the best of us as anglers, and meeting the challenge pays off handsomely in bent graphite and screaming reels. Ours may be the sport of gentlemen, but the gentleman may drool a little on his tie when he thinks of this hatch-to-come after a dismal fishless winter.
Ephemerella subvaria (Hendrickson) Mayfly NymphEphemerella subvaria (Hendrickson) Mayfly Nymph View 7 PicturesThis is another unusual brown Ephemerella nymph. The "fan-tail" which defines the Ephemerella genus is particularly evident on this specimen.
Collected February 7, 2004 from in
Added to Troutnut.com by on January 25, 2006
Male Ephemerella subvaria (Hendrickson) Mayfly DunMale Ephemerella subvaria (Hendrickson) Mayfly Dun View 9 PicturesI collected this male Hendrickson dun and a female in the pool on the Beaverkill where the popular Hendrickson pattern was first created. He is descended from mayfly royalty.
Collected April 19, 2006 from in
Added to Troutnut.com by on April 22, 2006
Male Ephemerella subvaria (Hendrickson) Mayfly SpinnerMale Ephemerella subvaria (Hendrickson) Mayfly Spinner View 11 PicturesI collected this beautiful male Hendrickson specimen as a dun, along with a female Hendrickson from the same hatch. Both molted into spinners in my house within a couple of days.
Collected April 23, 2007 from in
Added to Troutnut.com by on April 25, 2007

Mayfly Species Ephemerella invaria

These are very rarely called Hendricksons.
This species, the primary "Sulphur" hatch, stirs many feelings in the angler. There is nostalgia for days when everything clicked and large, selective trout were brought to hand. There is the bewildering memory of towering clouds of spinners which promise great fishing and then vanish back into the aspens as night falls. There is frustration from the maddening selectivity with which trout approach the emerging duns--a vexing challenge that, for some of us, is the source of our excitement when Sulphur time rolls around.

Ephemerella invaria is one of the two species frequently known as Sulphurs (the other is Ephemerella dorothea). There used to be a third, Ephemerella rotunda, but entomologists recently discovered that invaria and rotunda are a single species with an incredible range of individual variation. This variation and the similarity to the also variable dorothea make telling them apart exceptionally tricky.

As the combination of two already prolific species, this has become the most abundant of all mayfly species in Eastern and Midwestern trout streams.
Ephemerella invaria (Sulphur Dun) Mayfly NymphEphemerella invaria (Sulphur Dun) Mayfly Nymph View 8 PicturesThis small Ephemerella invaria nymph was at least a month away from emergence.
Collected April 19, 2006 from in
Added to Troutnut.com by on April 21, 2006
Male Ephemerella invaria (Sulphur Dun) Mayfly DunMale Ephemerella invaria (Sulphur Dun) Mayfly Dun View 7 Pictures
Collected May 26, 2007 from in
Added to Troutnut.com by on June 4, 2007
Male Ephemerella invaria (Sulphur Dun) Mayfly SpinnerMale Ephemerella invaria (Sulphur Dun) Mayfly Spinner View 12 Pictures
Collected June 3, 2005 from in
Added to Troutnut.com by on May 24, 2006

Mayfly Species Ephemerella needhami

These are very rarely called Hendricksons.
This small and slightly noteworthy mayfly appears during the finest hours of the year. Ernest Schwiebert describes an Ephemerella needhami day in Matching the Hatch:

"It was a wonderul morning, with a sky of indescribable blue and big, clean-looking cumulus clouds, and the water was sparkling and alive. You have seen the water with that lively look; you have also seen it dead and uninviting in a way that dampens the enthusiasm the moment you wade out into the current."


I have not fished a needhami emergence, but the exquisite nymphs show up often (though never abundantly) in my samples.
Ephemerella needhami (Little Dark Hendrickson) Mayfly NymphEphemerella needhami (Little Dark Hendrickson) Mayfly Nymph View 6 PicturesI photographed three strange striped Ephemerella nymphs from the same trip on the same river: this one, a brown one, and a very very striped one. I have tentatively put them all in Ephemerella needhami for now.
Collected June 9, 2005 from in
Added to Troutnut.com by on May 26, 2006
Ephemerella needhami (Little Dark Hendrickson) Mayfly DunEphemerella needhami (Little Dark Hendrickson) Mayfly Dun View 7 PicturesSee the comments for an interesting discussion of the identification of this dun.
Collected June 1, 2007 from in
Added to Troutnut.com by on June 4, 2007
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