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> > Drunella cornuta on the Brodhead at Stroudsburg PA

This topic is about the Mayfly Species Drunella cornuta

Though not as well known as the Hendrickson and Sulphur hatches of the Ephemerella genus, Drunella cornuta (Olive Morning Dun or Large Blue-Winged Olive) is nonetheless an important Eastern hatch.

Lloyd Gonzales, in his book Fly-Fishing Pressured Water, notes that this attractive olive-green mayfly can provide good-to-excellent morning fishing in the faster sections of many streams. He also mentions that it can hatch in surprising numbers and usually faces less competition for the trout's attention than many of the spring or evening-emerging ephemerellids. Yet, cornuta and its sister species have largely escaped the limelight. The renowned twilight hatches of big Ephemera drakes and many other popular mayfly species command fly fisher's attention at this time of year. As the days lengthen, fishing all of the available mayfly hatches would require a pretty long day astream, so most anglers choose to focus on the late afternoon and evening activity.

Nature seems to have several recurrent color themes, and one of these is gray-winged/olive-bodied aquatic insects. Perhaps this explains why the name "Blue-Winged Olive" is often held up as the poster child for common name confusion. It has been freely applied to a multitude of mayflies in various families, genera, and species. Prior to having a well-established common name, this mayfly was referred to by Gonzales as the Olive Morning Dun. However, it has already been added to the long list of "BWOs" on many Eastern/Midwestern hatch charts. Read more...

There are 3 more specimens...

The Discussion

ReifyApril 21st, 2014, 6:57 pm
Easton, Pennsylvania

Posts: 8
4/21/14 - Fished the Brodhead today at the last park before last bridge on PA 191 - downstream of huge riffle section so is a great tretch for this species. I didn't get there until around 1:00 PM, took a nap and started fishing at 2:00 and there were still cornuta coming off sparsely but steadliy - until 3:30 PM. Sparse rises, but I was entertained. Is that normal or could it be because the water is unusually cold this year. Are the males and females of the same size or is one larger - and of slightly more pale coloration at take-off from surface? It almost looked to me to be two different flies, but I'm sure they weren't.
WbranchApril 21st, 2014, 10:56 pm
York & Starlight PA

Posts: 2521
Are you very confident it was cornuta? Friends were there on Saturday and saw good numbers of Ep plurealis (Quill Gordons) In my experience in the NE PA and Catskills cornuta emerges much later in the season. I've never seen it before late May. Maybe you were seeing some Baetis? What size were the bugs?
Catskill fly fisher for fifty-five years.
EntomanApril 22nd, 2014, 8:07 am
Northern CA & ID

Posts: 2604
Hi Reify -

Anything is possible I suppose but as Matt says, the Morning Olive Dun (Gonzo) is normally seen much later in the season. It usually goes unnoticed becaue of hatching in the morning when most anglers are sleeping in from their late night pursuit of trout feeding on the big drakes that are also found at that time of year.
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman
BrookymanApril 22nd, 2014, 3:21 pm
Posts: 797
Also to add to this is the fact that Ephemerella cornuta is better know for being a ( AM ) hatch. Typically form 8: AM, till 12 noon, at best. As well HATCH'S II has them listed for (PA) to emerge between May 14th & June 7th, with the peak range being May 25th till 3rd of June. Of course higher & colder water could cause some later in the day hatch's but not right now.

Epeorus pleuralis is a mid-day hatch from 1: PM till 2:30 PM form mid May till early June in your area.. Their emerging time frame is similar to Ephemerella cornuta. From my personal experience I have never seen hatching of any significant numbers for the Quill Gordon or Epeorus pleuralis ever. It is always a sparse hatch at lease for me it is.

However The Baetis tricaudatus hatch's from 11: AM till 4: PM in your area from late March till early May. Baetis tricaudatus often hatch's in bigger numbers especially right now cause this is around their peak. For the most part it is still to early for cornuta & pleuralis.

I think that the BWO Baetis tricaudatus is the most likely mayfly for this post as a possible ID. However if you have a photo and or measurements that could really define which specie or genus we are talking about here and that would be great.

So now is the time for others to correct me and or add more to this.

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ReifyApril 22nd, 2014, 7:01 pm
Easton, Pennsylvania

Posts: 8
My confusion now with it being a Quill Gordon is that it definitely had three rather under-accented tails; these were pale gray/whitish and on many specimins were short, almost limp-looking. The QG has only two, as far as I know and they are quite stiff and barred. Also, the wings were very deep lead-colored. As for size, I'd call it a #14, but large #14 - they were large flies and the abdomen in particular was very heavy/ rotund with the segmentations alternating pale maroon and olive on some and more uniform - the colors more approaching each other on other samples. Cornuta is known for color transitions from lighter to darker while adrift. Finally, when on a hard surface, they held their abdomens in a very much upward-arching toward the posterior position. The Quill Gordons I've seen hatching had a darker abdomen in general, lighter-colored wings and the segmentations ran from less apparent to obvious (I carry some with both the lesser and greater amount of barring). To clarify, I'm not a hugely experienced Catskill Mayfly fisherman. I fish mostly in the Lehigh Valley where we lost so many of our mayflies long ago. I'm nearing retirement and hope to travel to and fish the upper Delaware, Beaverkill, Willowemoc, etc. as time allows. I hope to see and learn about what's left of all I've read about over my 50 years of dabbling in the art.
BrookymanApril 22nd, 2014, 7:17 pm
Posts: 797
The tails are a big clue. The only others that hatch at this time of years and have 3 tails is (Ephemerella subvaria) & (Ephemerella invaria-rotunda). The subvaria is typically a pinkish olive maroon colored and the rotunda form can be very olive in color to a drab yellowish-olive. I would say they were the rotunda form of invaria. They can't be a Baetis cause they have 2 tails. Your tail description fits both subvaria & invaria-rotunda. You most likely were seeing both species as they often overlap and that is knowledge according to the book Hatch's II.

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JOHNWApril 22nd, 2014, 8:55 pm
Chambersburg, PA

Posts: 452
I am going to second the subvaria vote. Given the prevailing weather patterns it is still a little early for rotundas (they usually coincide with with the second to third rounds of the Stanley cup playoffs on your LV streams and maybe a week later in the Poconos).
The Broadheads is not an overly rich stream so colors tend to be a little muted. Subvaria is also known for color variation between genders (Hendricksons vs Red Quill) as well as in individuals as they "age" after emergence often starting almost bright pink and quickly fading to the above described gray/tan/olive almalgamation.

That and.70 $ still won't yet you a cup of coffee.
"old habits are hard to kill once you have gray in your beard" -Old Red Barn
BrookymanApril 22nd, 2014, 10:18 pm
Posts: 797
Hey JW that water info makes me agree with you on E subvaria. Ya they can have great variation just like the rotunda. Here where I am the rotunda & invaria start to come off just around the time my subvaria peak.

So down there they might be going off as well. My subvaria start to peak on opening day this weekend and are gone by May 3rd. Then the invaria & rotunda snow storms start.

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MartinlfApril 23rd, 2014, 11:44 pm
Palmyra PA

Posts: 2933
Subvaria also vary a great deal in color from stream to stream. Females are typically larger and lighter than males. It seems the most likely ID. A buddy who fishes the Brodhead told me tonight that subvaria were hatching there.
"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell
BrookymanApril 24th, 2014, 12:58 am
Posts: 797
I agree for sure, and having fresh reports from that water,, well that's the icing on the cake.
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JOHNWApril 24th, 2014, 4:34 pm
Chambersburg, PA

Posts: 452
Being a Flyers fan the observation occured because the rotundas are typically the poultice for the broken heart of a hockey fan whose team just got eliminated. ;)
The "grail date" for rotundas in that part of PA is typically May 15 while the Hendricksons tend toward mid to late April (late March in really mild winters). Since or spring tends to be a little more gradual the hatches are a little more spread out than in northern climes. There are times where there is a week or two gap between the "early dark mayflies" and the "late light mayflies". Well at least in my humble observations.
"old habits are hard to kill once you have gray in your beard" -Old Red Barn
BrookymanApril 24th, 2014, 4:50 pm
Posts: 797
For some reason I am not sure why they overlap here at least on this one stream system they do. It is an advantage to me because the fish are not so selective because the subvaria spinner and the rotunda duns often take place together starting in about a week. My subvaria peak happens just after opening day being the 26th of April. By the time May 4th comes both are in full swing or so to speak. By May 15 there are some subvaria, tons of rotunda, and now my invaria comes into play. Its kind of a cool thing but it can make picking a pattern difficult. Also this system warms very quickly so inside a 2 week span the water temperature can go from 42* to as high as 55* that may have something to do with the overlapping issue on this stream in particular.

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