Mayfly Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)
Taxonomic Navigation -?-
Kingdom Animalia (Animals)
» Phylum Arthropoda (Arthropods)
» Class Insecta (Insects)
» Order Ephemeroptera (Mayflies)
» Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)
| Genus in Ephemerellidae |  |  |
| Attenella | 5 | 28 |
| Caudatella | 0 | 0 |
| Dannella | 0 | 0 |
| DrunellaBlue-Winged Olives | 8 | 60 |
| EphemerellaHendricksons, Sulphurs, PMDs | 122 | 556 |
| EurylophellaChocolate Duns | 15 | 64 |
| Serratella | 1 | 6 |
| Timpanoga | 0 | 0 |
2 genera aren't included.
Common Name
| Match | Common Name |
 | Hendricksons, Sulphurs, PMDs, BWOs |
Where & When
A curious property of this family is that the males and females often inhabit different parts of the stream. In many species the males and females are of different sizes and colors, it your fly may need to match the main gender emerging from your stretch of the river.Hatching Behavior
These are fantastic dry-fly insects. Behavior varies by species, but almost all have excellent qualities for the angler. Some emerge laboriously in the surface film, where emerger and floating nymph patterns are excellent. Others emerge on the bottom, during their rise to the surface, or immediately subsurface; most of these species are good wet fly fare and they take a very long time to dry their wings once they reach the surface. There they ride like sailboats in classic mayfly style, fluttering occasionally, and are imitated by classic mayfly patterns.Many species are especially prone to being stillborn (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.) or crippled, and trout are especially fond of this wounded prey and our crafty imitations.
View Full Size
Spinner Behavior
Most species return to the stream as spinners one day after they emerge. Spinner falls are usually concentrated over the riffles.Nymph Biology
Environmental Tolerance: Most species are unusually tolerant of silt, warmth, and pollution. Some, like Ephemerella subvaria, are not.
Nymphs of this family are a gift to the angler, because many have the peculiar habit of swimming up and down between the surface and the bottom several times before actually emerging. I do not know what actual biological purpose these seeming "practice runs" serve, but they expose the slow-swimming nymphs to the trout.Several authors, including , write that some of the nymphs crawl to the high tips of rocks and other objects prior to emergence, where they may be picked off their perches by peckish trout. In my experience photographing the nymphs underwater in April, they often graze in such exposed locations even when they aren't about to emerge.
Between their tendency to be in exposed places, the unsure footing of some species in fast water, and behavioral drift (Behavioral drift: The nymphs and larvae of many aquatic insects sometimes release their grip on the bottom and drift downstream for a while with synchronized timing. This phenomenon increases their vulnerability to trout just like emergence, but it is invisible to the angler above the surface. In many species it occurs daily, most often just after dusk or just before dawn.), the nymphs of this family are important to trout year-round.
166 Mayfly Specimens in the Family Ephemerellidae:
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.
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.Region: Catskills
Collected Apr 19, 2006
Added Apr 22, 2006
Attenella attenuata (Small Eastern Blue-Winged Olive) Mayfly Spinner
View 11 Pictures
View 11 PicturesRegion: Upper Midwest
Collected Jul 1, 2005
Added Apr 22, 2006
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.
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.Region: Northeast
Collected Apr 23, 2007
Added Apr 25, 2007
9 Streamside Pictures of Ephemerellidae Mayflies:
View Full Size
Here's an above-the-water view of a stillborn (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).
In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
This Ephemerella invaria sulphur dun got stuck in its shuck (
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).
Here's an underwater view of the pupal shucks of several already-emerged Brachycentrus numerosus caddisflies.
In this picture: Mayfly Species Ephemerella invaria (Sulphur).
37 Underwater Pictures of Ephemerellidae Mayflies:
This Ephemerella subvaria (Hendrickson) nymph picture is one of my favorites.
In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
There's a large Ephemerella subvaria nymph in the top left.
In this picture: Insect Order Trichoptera (Caddisflies), Mayfly Species Ephemerella invaria (Sulphur), and Mayfly Species Ephemerella subvaria (Hendrickson).
In this picture: Insect Order Trichoptera (Caddisflies), Mayfly Species Ephemerella invaria (Sulphur), and Mayfly Species Ephemerella subvaria (Hendrickson).
Recent Discussions of Ephemerellidae
does color=species? 5 Replies »
if the "sulphurs" from one stream are peach-colored, and from another are nearly white, are they the same or different bugs? would they hatch at different times?
as a tyer, i just make them different colors, but d'you think they would hatch at around the same week or so?
ReplyWow, they really can take forever to get off the water 32 Replies »as a tyer, i just make them different colors, but d'you think they would hatch at around the same week or so?
Posted by Troutnut on Jun 14, 2006 in the species Ephemerella dorothea
Last reply on Aug 15, 2007 by Wiflyfisher
I watched quite a few of these guys emerge tonight. (I think -- they seemed too small and light to be Ephemerella invaria, though I didn't bring one home to check under the microscope.) It was a cool evening but not cold, and they were emerging on the slow flats of a large midwestern spring creek. I watched several of them drift 50+ feet on the very slow-moving water, slowly rising up out of the surface film. Their emergence was sporadic and lucky for them the trout were also sporadic. Many were eaten but others went ignored for their entire lengthy drifts.
Later in the evening I was bested by a half-dozen rising trout. The sulphurs were still emerging, and a mix of spinners was starting to appear on the water, but I didn't get so much as a splashy refusal from several rising fish, even in the low light of dusk. My best guess is that they were picky feeders keying on a stage of Ephemerella dorothea mayflies.
ReplyAnyone know more about Ephemerella septentrionalis? 4 Replies »Later in the evening I was bested by a half-dozen rising trout. The sulphurs were still emerging, and a mix of spinners was starting to appear on the water, but I didn't get so much as a splashy refusal from several rising fish, even in the low light of dusk. My best guess is that they were picky feeders keying on a stage of Ephemerella dorothea mayflies.
Posted by Troutnut on May 18, 2007 in the species Ephemerella septentrionalis
Last reply on Jun 18, 2007 by Konchu
I found about one sentence on these in Gonzo's book, and haven't seen them mentioned anywhere else in fly fishing literature. Nor is any of the scientific literature I have on them particularly interesting (just descriptions). Now that I've collected a few and see what unique-looking nymphs they've got, I'm really curious about them.
ReplyWhen does a Hatch happen? 8 Replies »Posted by TheMidge on May 10, 2007 in the species Ephemerella subvaria
Last reply on May 26, 2007 by Greenghost
I was hoping I could get a little info on what effects a Hatch. Air Temp? Water Temp? A combination? I'm trying to determine the best time to catch a hatch on stream near me, as I have a small window to fish in on a short trip home. I am expecting to see Hendrickson's, as it's the right time of year (or so I have been told) for this stream. What's the best way to guess?
ReplyMidwest Lata Emergence 20 Replies »Posted by DarkDun on Mar 4, 2007 in the species Drunella lata
Last reply on May 2, 2007 by Taxon
The D.Lata emerges in Michigan waters at 10 AM on the dot and stops at noon from about June 25 thru July 10. I have fished this hatch avidly for years and find it very punctual on moderately overcast days. Sunny days make it much shorter duration, about 30 minutes. A size 14 imitates it perfectly with dark dun wings, bright olive green body and med dun tails and legs at emergence. The body color does change to dark green after a while.
The D.Lata also is significant in PA Northern Streams in Mid May.
I have not encountered it in the South Appallacian streams as yet. I fish some smaller BWO (#16-20) in NC but none so large as D. Lata.
ReplyThe D.Lata also is significant in PA Northern Streams in Mid May.
I have not encountered it in the South Appallacian streams as yet. I fish some smaller BWO (#16-20) in NC but none so large as D. Lata.
There are 3 more topics.
New features!
