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Mayfly Genus Ephemerella (Hendricksons, Sulphurs, PMDs)

Taxonomic Navigation -?-
Species in EphemerellaNumber of SpecimensNumber of Pictures
Ephemerella aurivillii18110
Ephemerella dorothea dorotheaPale Evening Dun211
Ephemerella dorothea infrequensPale Morning Dun23
Ephemerella excruciansPale Morning Dun524
Ephemerella invariaSulphur Dun45187
Ephemerella needhamiLittle Dark Hendrickson941
Ephemerella subvariaHendrickson34162
Ephemerella tibialisLittle Western Dark Hendrickson11

11 species aren't included.
Common Name
Pictures Below
This genus contains the legendary Hendricksons and Sulphurs of the East and the equally important Pale Morning Duns of western waters.

No scientific name in American angling literature is more renowned and at the same time capable of more confusion than the genus name "Ephemerella." It is important that anglers have a good overall grasp of its taxonomic history if they are to make any sense out of the rich literary heritage involving this mayfly name.

By the time American angling literature began to take serious note of entomology in the decades of the early to mid 20th century, Ephemerella was considered a "super-genus" in the family Baetidae, containing all of the important species to anglers in the subfamily Ephemerellinae. Taxonomists organized them by association with "type" species that were referred to as "groups" within this very large and unruly genus.

This organizational structure held sway until the 70's when they were recognized as separate from the Baetidae with their own family, the Ephemerellidae. The "groups" (after a little name changing and reorganization) were given subgenus status, but in conformance with taxonomical convention,the nomenclature retained the use of the name Ephemerella when referring to individual species genus status. More change occurred towards the end of the century as consensus formed around the subgenera achieving full generic status. The broad use of Ephemerella was then dropped in favor of the new generic names.

These changes were necessary in that they addressed many problems exposed in older taxonomies. Unfortunately, all during this period the changes were reported with varying degrees of accuracy and acceptance. For anglers this was exacerbated by the continued use and reliance on older entomology texts in many circles. Be that as it may, recent or updated angler entomologies now recognize that many of the old Ephemerella species are spread out among several genera in the Ephemerellidae family. These include the various Blue-Winged Olives and Western Green Drakes of the Drunella genus as well as several important species scattered in genera like Attenella and Serratella, to name a few.

Despite these revisions in classification, the Ephemerella genus still contains arguably the most important species in North America, and remains a "super-genus" to anglers.

There is a lot of variation; refer to the genus species hatch pages for details.
  

Where & When


Regions: East, Midwest, West

Time Of Year (?): Mostly in the spring in the East, all season in the West

Ephemerella species inhabit most types of water and can be found at any time of the season depending on locale. This genus is very important in the East and Midwest, where the major species hatch in the spring and a few continue into the summer. In the West, the species comprising the Pale Morning Dun complex produce the superhatches of international fame that can be found somewhere in this vast region virtually the entire season.

Hatching Behavior


Variable - see species

Spinner Behavior


Time Of Day: Evenings in the East, mid-mornings in the West (with exceptions)

Habitat: Riffles if available, otherwise specific locations based on several considerations.
The concentrated evening spinner falls of many species in this genus are some of the best fly-fishing events of the spring in the East. In the West, many mid-morning spinner falls have achieved legendary status.

They are also one of the groups of mayflies prone to the unfortunate behavior of mating and ovipositing over blacktop roads hundreds of yards from the river.

Pictures of 129 Mayfly Specimens in the Genus Ephemerella:

Specimen Page:1234...14
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 the Beaverkill River in New York
Added to Troutnut.com by Troutnut on April 22, 2006
Ephemerella dorothea dorothea (Pale Evening Dun) Mayfly NymphEphemerella dorothea dorothea (Pale Evening Dun) Mayfly Nymph View 6 PicturesI keyed this nymph carefully under a microscope to check that it's Ephemerella dorothea.
Collected May 29, 2007 from Paradise Creek in Pennsylvania
Added to Troutnut.com by Troutnut on June 4, 2007
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 Fall Creek in New York
Added to Troutnut.com by Troutnut on April 25, 2007
Specimen Page:1234...14

7 Streamside Pictures of Ephemerella Mayflies:

Streamside Photo Page:12
This Ephemerella invaria sulphur dun got stuck in its shuck trying to emerge.  This isn't exactly a "natural" pose for a photograph, but it kind of shows what an emerger pattern could look like.  In this picture: Mayfly Species Ephemerella invaria (Sulphur Dun). From the Neversink River in New York.
This Ephemerella invaria sulphur dun got stuck in its shuck (
Here's an underwater view of the pupal shucks of several already-emerged Brachycentrus numerosus caddisflies.
Here's an underwater view of the pupal shucks of several already-emerged Brachycentrus numerosus caddisflies.
Shuck: The shed exoskeleton left over when an insect molts into its next stage or instar. Most often it describes the last nymphal or pupal skin exited during emergence into a winged adult.
)
trying to emerge. This isn't exactly a "natural" pose for a photograph, but it kind of shows what an emerger pattern could look like.

In this picture: Mayfly Species Ephemerella invaria (Sulphur Dun).
Date TakenMay 20, 2007
Date AddedJun 5, 2007
AuthorTroutnut
CameraPENTAX Optio WPi
Here's an above-the-water view of a stillborn Ephemerella subvaria dun which I also photographed from below the water.  In this picture: Mayfly Species Ephemerella subvaria (Hendrickson). From Mongaup Creek in New York.
Here's an above-the-water view of a stillborn (
This stillborn Ephemerella subvaria dun is trapped in its shuck.
This stillborn Ephemerella subvaria dun is trapped in its shuck.
Stillborn: In fly fishing, a stillborn insect is one which got stuck in its nymphal or pupal shuck during emergence and floats helplessly on the surface instead of flying away. It is a specific class of cripple, although it is sometimes used interchangeably with that term.
)
Ephemerella subvaria dun which I also photographed from below the water.

In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
Date TakenApr 19, 2006
Date AddedApr 22, 2006
AuthorTroutnut
CameraPENTAX Optio WPi
Shed exoskeleton from what was very likely an Ephemerella aurivillii nymph that emerged on this rock.  In this picture: Mayfly Species Ephemerella aurivillii. From Mystery Creek # 170 in Alaska.
Shed exoskeleton from what was very likely an Ephemerella aurivillii nymph that emerged on this rock.

In this picture: Mayfly Species Ephemerella aurivillii.
StateAlaska
Date TakenJul 11, 2012
Date AddedJul 14, 2012
AuthorTroutnut
CameraCanon PowerShot D10
Streamside Photo Page:12

37 Underwater Pictures of Ephemerella Mayflies:

Underwater Photo Page:12345
This picture from below shows a stillborn Ephemerella subvaria (Hendrickson) dun drifting on the surface amidst a number of shed pupal skins from Brachycentrus caddisflies which were heavily hatching that day.  In this picture: Mayfly Species Ephemerella subvaria (Hendrickson) and Caddisfly Species Brachycentrus appalachia (Apple Caddis). From the East Branch of the Delaware River in New York.
This picture from below shows a stillborn (
This stillborn Ephemerella subvaria dun is trapped in its shuck.
This stillborn Ephemerella subvaria dun is trapped in its shuck.
Stillborn: In fly fishing, a stillborn insect is one which got stuck in its nymphal or pupal shuck during emergence and floats helplessly on the surface instead of flying away. It is a specific class of cripple, although it is sometimes used interchangeably with that term.
)
Ephemerella subvaria (Hendrickson) dun drifting on the surface amidst a number of shed pupal skins from Brachycentrus caddisflies which were heavily hatching that day.

In this picture: Mayfly Species Ephemerella subvaria (Hendrickson) and Caddisfly Species Brachycentrus appalachia (Apple Caddis).
Date TakenApr 19, 2006
Date AddedApr 22, 2006
AuthorTroutnut
CameraPENTAX Optio WPi
This is a close-up underwater view of a stillborn Ephemerella subvaria (Henrickson) female dun.  In this picture: Mayfly Species Ephemerella subvaria (Hendrickson). From the East Branch of the Delaware River in New York.
This is a close-up underwater view of a stillborn (
This stillborn Ephemerella subvaria dun is trapped in its shuck.
This stillborn Ephemerella subvaria dun is trapped in its shuck.
Stillborn: In fly fishing, a stillborn insect is one which got stuck in its nymphal or pupal shuck during emergence and floats helplessly on the surface instead of flying away. It is a specific class of cripple, although it is sometimes used interchangeably with that term.
)
Ephemerella subvaria (Henrickson) female dun.

In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
Date TakenApr 19, 2006
Date AddedApr 22, 2006
AuthorTroutnut
CameraPENTAX Optio WPi
The white blotches on this rock are Leucotrichia caddisfly cases, and the wispy tubes are cases made by a type of midge.  In this picture: Caddisfly Species Leucotrichia pictipes (Ring Horn Microcaddis), Mayfly Species Ephemerella invaria (Sulphur Dun), and True Fly Family Chironomidae (Midges). From the Namekagon River in Wisconsin.
The white blotches on this rock are Leucotrichia caddisfly cases, and the wispy tubes are cases made by a type of midge.

In this picture: Caddisfly Species Leucotrichia pictipes (Ring Horn Microcaddis), Mayfly Species Ephemerella invaria (Sulphur Dun), and True Fly Family Chironomidae (Midges).
Date TakenMar 24, 2004
Date AddedJan 25, 2006
AuthorTroutnut
Underwater Photo Page:12345

Recent Discussions of Ephemerella

So is Ep Infrequens now known as Ep Dorothea? 20 Replies »
Posted by Wbranch on Feb 17, 2008 in the species Ephemerella dorothea infrequens
Last reply on Jul 1, 2014 by Crepuscular
These mayflies look more like the Sulfurs I see on the Delaware system than the PMD's I see in Montana. The Montana mayfly has a distinct yellow leading edge to an overall light dun gray wing and the abdomen and thorax have a more light greenish/yellow cloration so how is it that Infrequens is now known as Ep Dorothea Dorothea?
ReplyInvaria - Dorothea confusion 17 Replies »
Posted by Entoman on Feb 1, 2012
Last reply on Feb 7, 2012 by Entoman
The following is from an older post of Gonzo's.

It's been my suspicion for quite some time that a good part of the credit given to dorothea for creating the later, lighter-colored "little sulphur" hatch should probably go to the same species (or species complex) that creates the earlier, larger, darker hatch--E. invaria. Many anglers who fish the small suphurs on valley limestone streams in my home state believe (or have been led to believe) that they are fishing the dorothea hatch. Close inspection of the mayfly that causes the activity usually doesn't bear that out. Most of the true dorothea hatches seem to come from mountainous areas where the streams are faster and have rockier bottoms.

All of the specimens in this section are from PA, and this seems to provide a good case in point. This specimen and the nymph (#766) are good examples of dorothea, and they both came from sections of the Brodheads in the Poconos. The other specimens came from big limestoners and appear to be invaria. Notice that all of the dun and spinner specimens, except for this one, have banded tails (dark markings at the segments). As far as I know, this is not characteristic of the Eastern version of dorothea (E. dorothea dorothea), but it is a trait of invaria.


I've often speculated the same thing as I've seen examples of eastern invaria that look virtually identical to some of infrequens out West. Compare the specimen I posted http://www.troutnut.com/specimen/1013 to this one of Spence's http://www.troutnut.com/im_user_ident/picture_219_large.jpg Any thoughts guys?
ReplyPMD Spinner - Egg sack color? 19 Replies »
Posted by Wbranch on Jan 26, 2010 in the species Ephemerella excrucians
Last reply on Jul 1, 2011 by Konchu
Do any of you entomologist types know the true color of the PMD spinner? Dorothea or excrucians. Where I fish in MT there are huge spinner falls, many spents are on the water in the morning and others fall again at various periods during the day. I'd like to tie some with egg sacks as I saw many in July but forgot what color they were. Thanks.
ReplyAw Shucks 10 Replies »
Posted by Martinlf on May 19, 2009 in the species Ephemerella invaria
Last reply on Jul 24, 2009 by Martinlf
OK, this is going to seem like a major duh experience for some of you, but the other night I found a sulphur spinner on the door of a bathhouse in a campground I was staying at. Looking for other bugs I then saw a pale nymph shuck on the door. I was totally confused. A nymph this far from the stream? Was this some alien bug? Looking closer I noticed that the shape was too slender for a nymph and that the wing pads were more like little protruding pockets--and it hit me. Spinner shuck. I knew that mayflies molted to produce a spinner, but I had thought the shuck would be more insubstantial--something that would be flimsy and lack form. This was so cool, and at the same time I felt so silly for thinking it could somehow have been a nymph shuck. It's the first spinner shuck I've seen, but I assume that I'll start seeing them everywhere now, like a new word you learn. Anybody else have a spinner shuck story?
Replypmd hatches in ny? 3 Replies »
Posted by Trouthunter on Apr 18, 2009
Last reply on Apr 19, 2009 by GONZO
I was recently told by a close friend of mine that in the southertier of ny ( finger lakes region) that we have very good hatches of pmds. I was hoping that someone could confirm this or otherwise before I tye up patterns. I have seen what I believe are sulphurs with slightly the same body and wing coloration but again thought that these couldn't be the famed insect.
Reply
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