Large Sulphur - Ephemerella Invaria



Staff member
Dec 13, 2021
Here is one of my bugs from the Little J on Sunday.

Will edit the post after we discuss.

Tails: 3
Hind wing: present
Costal projection on hind wing: yes
Fore wings: plain
Viens do not diverge at base of fore wing
Body 10-11 mm
Hatching from 1:00 pm - 8:00 pm

First photo on the stream Sunday , second from the kitchen studio this morning

Place your bets and why?

Locations found: Central Pennsylvania


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Ephemerella Invaria - Sulpher

Reasoning, do I get credit for showing my work? (no seriously, more as an example to the beginners at this).

Noticing plain wings, large hind wing, 3 tails, that already narrows you down to these Genus's:

Anthopotamus, Attenella, Baetisca, Caudatella, Drunella, Ephemerella, Leptophlebia, Paraleptophlebia, Serratella, Timpanoga

Using the size of 10-11 mm given, you can eliminate Attenella, Serratella, and Timpanoga. That leaves us with:

Anthopotamus, Baetisca, Caudatella, Drunella, Ephemerella, Leptophlebia, Paraleptophlebia

It is not a Baetisca (armored mayfly, wrong basic body shape), Drunella, Leptophlebia, or Paraleptophlebia (color too light).

So we're left with anthopotamus, caudatella, and ephemerella genus's. Now is where it starts getting a little bit tougher.

Anthopotamus - golden drake. Could be, but I've seen them and it just doesn't "look" like one. So I'm gonna say NO.

Caudatella - listed by Troutnut as a western genus, not eastern. So I'm gonna say NO.

Ephemerella - ding ding ding, we have a winner.

Now, which species? Throw out the hendricksons in the ephemerella genus, this is too light colored for that.

So, of the more common eastern species, we have:


These two species make the primary SULPHER hatch. Now, Invaria comes first, and typically is like a size 14-16, which corresponds about from 9-12 mm. Dorothea comes later and are about 7-9 mm in length (size 16-18).

So, based on size, I'm guessing you have yourself a Ephemerella Invaria - commonly known as a sulpher, or "big sulphers" for people that separate the 2 main species.

I saw:
Three tails > Body size 11mm > Fore wing views don't diverge at base> Costal projection on hind wing

Which takes you to:
Drunella cornuta (BWO) or Ephemerella invaria (Large Sulphur)

The lighter body coloring of the Ephemerella invaria (sulphur) fits verse the darker body and smaller size you would find with the Drunella cornuta (BWO).

Again as with all hatches a couple of weeks early in 2012!
I would argue that you couldn't use body size to distinguish between drunella and ephemerella invaria. The Drunella cornutas (late olives, or large olives as I call them) I've run across are often 14's and 16's. And that's roughly the same size as ephemerella invaria, and bigger than dorothea.

Nonetheless, agree with you on the final ID, and that you can distinguish between those two on color.

The veining and costal lobe I kind of leave out of ID's. It is a quicker method to get to the same place, but in pictures it's often hard to distinguish either, and even harder in person. Heck, I often struggle to see whether there is a large hind wing or not, much less see a lobe on it.
Do you know of other indicators, besides body coloring, between Drunella cornuta (BWO) or Ephemerella invaria (Large Sulphur)?

No, I don't, just coloring of body and wing, and timing. The Drunella's typically being a June thing, after most of the sulphers and especially invaria are pretty much done. I don't think they are two that are confused with one another very often.

Though, even if you did confuse them, it wouldn't make much difference. Same family. Same general hatching and spinner fall characteristics. And because of that, generally the same tactics.

Sulphers are more often confused with various cahills (maccaffertium genus), pink ladies (epeorus vitreus), and the like. And those indeed have different characteristics which are important to fishermen. Where the nymphs go before emerging, how they emerge, when the spinners come, whether they fall over riffles or pools, etc.

Likewise, Drunellas are most often confused with various species of Baetis, in fact, they share a freakin common name in BWO. Yet they are different enough in characteristics to be a whole different ball game, they deserve separate names IMO.
Well the fish can get confused too. They wouldn't take my sulphur patterns yesterday, but did take my Hendrickson & Adams when I put them on.
Where were you fishing Dave? I made a mid afternoon trip up to the J and was pleasantly surprised to encounter a sulphur hatch (definitely invaria). I fished till dark and the fishing was great... No spinner fall to speak of, so the hatch is just getting started.
Drunellas are mostly a morning hatch too, and a totally different color. However both species have rusty spinners after the final molt.
Central PA, April 29th, 2012, between 2PM and 4PM.

E. invaria

Two tails, not a sulphur.
Great picture! Looks like a tail broke off, but on closer inspection, it's there, just twisted toward the camera. Definitely three tails, and the picture quality tells the "tail". :-D
Thanks HA. The third tail is definitely there. Its pointing almost directly at the camera so it gets lost a little.

Found this guy hanging on a tree when I got my fly stuck in it.
Cory, That's a Hendrickson [looks like to me].Please repost this to the E. Subvaria topic so you get proper credit for the photo.