Bugs on Hammer

sarce

sarce

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Ran into a solid hatch of what I believe were two different kinds of light-colored mayflies last night on Hammer. I am not sure what the first one is. White fly?

2a and 2b are the same bug. Appears to be some sort of drake. I am only really familiar with Green drakes and this one looked a little different and slightly smaller. Although when I was there two weeks ago, I captured one mayfly that was definitely a green drake so I guess it could be one.

Sorry I couldn't get better pics with my cell phone.
 

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Neither are "whiteflies." Hazarding guesses is something close to a grey fox and some form of cahill. Not enough identifiers for even pcray to be 100% sure.
 
Definitely not a white fly in the first. (Their legs are practically non-existent.)

Other than that, kinda hard to tell from the pictures. The "arm bands" on the upper forelegs suggests that they might both be from clinger type nymphs; the lower one might be a light cahill. ( would certainly use a light cahill to imitate it).
 
cream cahill spinner and a light cahill spinner
 
Look like Cahills. I've seen a few on our local brookie streams lately.
 
Cahills. Hammer has a good cahill hatch (not as good as the sulphurs)
 
Thanks all. I Did not know Cahills got that large. They were impressive.
 
sarce wrote:
Thanks all. I Did not know Cahills got that large. They were impressive.

How big were they?

If they were really big, they might have been Yellow Drakes.

You can check out pictures of those (and Cahills) on Troutnut.com.
 
Yeah those last two are big...I'd say some sort of drake. Even the wings are a coarsly mottled like a drake. and the top of the abdomen is contrasting too much for Cahills.
 
Maurice wrote:
Yeah those last two are big...I'd say some sort of drake. Even the wings are a coarsly mottled like a drake. and the top of the abdomen is contrasting too much for Cahills.

They're not drakes. The dead give away is the "arm bands" on upper segment of the front legs -- generally, only heptagenids (clinger nymph mayflies) have them. (None of the drakes do.)

There's probably a dozen or more species within that family that are called "Cahills". They vary in color with exact species, gender, dun vs spinner, location where they're found, and time of season. You can't go by color.

Some of them are quite large. Here's a picture from troutnut that shows one that's somewhere between a size 10 and a size 8:

Troutnut light cahill

 
Yeah, really, and MB's can be fit into the same group of bugs. They are very closely related to cahills.
 
The photo is a little out of focus but I'm pretty sure the two bottom pictures are Ephemera varia. yellow drake spinner. The head is not that of a heptageniid. The banding on the front legs is at the joint between the femur and tibia.The abdominal markings look to be E. varia
 
I looked up The yellow drake pictures mentioned by troutbert. I'm not convinced they are a match, but there were only three pics on troutnut. The mottling on the wings definitely does not match any Cahill pic that I can find. The one i posted here was on the larger side of what I saw. I'm not great at guessing hook size but I would say easily a #10. Possibly #8.

I am leaning drake now but I really don't know what kind it would be. My first thought on the stream was a small green drake. I have seen GDs/coffin flies that size on streams here in centre county- not in the same league size wise as the ones you see on Penns.

For those who said yellow drake. What identifiers do you use to tell the difference between those and green drakes?

 
They are too small to be drakes, look at the size of the bug compared to the guys hand and fingers. Not even big enough to be a MB.
 
Chaz wrote:
They are too small to be drakes, look at the size of the bug compared to the guys hand and fingers. Not even big enough to be a MB.

Well I'd have to disagree with that assessment. First you have to consider camera angle. Then the same approximate distance on my hand the from the same portion of the finger as in the photo of the mayfly is almost 18mm, and I do not have a giant hand or a small one, pretty much average size. The size range for most of the Ephemera varia that we have here in PA is from 13-20 mm. The specimen in question fits in that size range. These mayflies like most of the Ephemerids have very large size ranges. For example look at a female green drake from Penns compared to a male from Pine or Kettle creeek there's a big difference. My records show that theE. varia from the yellow breeeches that I have collected have a size range from 15-18 mm for the males and 17-21mm for the females. The free stone versions are much smaller, so although size may be a distiguishing characteristic, it may not be the most relaiable one. A size range may be a better one. The next character to look at would be the head. In the fuzzy photo you can still see that the eyes are wide set and the head is not flattened like that of a heptageniid mayfly. Instead the head is small in proportion to the metanotum again fitting the description of the Ephemerids. The abdominal markings look to be a close fit the description of Needham, 1920, 1935, and Burks 1953 for Ephemera varia. There are no heptageniids with adult abdominal markings like this. The dark markings on the crossviens also fit the description of Ephemera varia again see Needham 1920, Needham 1935, and Burks 1953. The fore legs have the banding at the joint of the femur and tibia, again fitting the description of E. varia. And then you have the timing, which as well all know is not a great way to identify a mayfly, but in general, it's yellow drake time in PA.

As to how to tell the difference between E.. varia and E. guttulata the obvious difference in the dun statge is the overall coloring of the mayfly dorsal abdominal markings. In general, because again there is a lot of variation in the coloration of mayflies, the E. guttulata will be darker in coloration with a slight green hue in the wings and a yellow creamy coloration to the ventral side of the abdomen in the dun stage than the more lighter creamy whitish yellow of E. varia.In E. guttulata the dorsal side of the abdomen will be a dark continuous band running the whole lenght of the abdomen. In E. varia the dorsal abdominal portion of the mayfly will have a series of dark markings with a lighter medial stripe along the entire abdomen. In the spinner stage the dorsal stripe on E. guttulata is not there and the abdomen is without marking for the most part. The dorsal portion of the abdomen retains the markings of the dun stage in E. varia.
 
That was super helpful, thanks! Based on what you said I agree it was a yellow drake (E. Varia). your size estimate was spot on. I measured those two spots on my hand and it's 17-19 mm.

For comparison here is the lone Green Drake I saw on the same stream two weeks prior.
 

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You cannot consider a flies identification without taking into account the habitat, Yellow Drakes are found only in water of the highest quality, I doubt that description fix the Breeches or Hammer Creek. They are pretty rare in PA. As to the size the drakes are big and the flies pictured are not as big as I'd expect Yellow Drakes to be.
With that in mind I still think they are cahills of some sort.
 
crepuscular wrote:
Chaz wrote:
They are too small to be drakes, look at the size of the bug compared to the guys hand and fingers. Not even big enough to be a MB.

Well I'd have to disagree with that assessment. First you have to consider camera angle. Then the same approximate distance on my hand the from the same portion of the finger as in the photo of the mayfly is almost 18mm, and I do not have a giant hand or a small one, pretty much average size. The size range for most of the Ephemera varia that we have here in PA is from 13-20 mm. The specimen in question fits in that size range. These mayflies like most of the Ephemerids have very large size ranges. For example look at a female green drake from Penns compared to a male from Pine or Kettle creeek there's a big difference. My records show that theE. varia from the yellow breeeches that I have collected have a size range from 15-18 mm for the males and 17-21mm for the females. The free stone versions are much smaller, so although size may be a distiguishing characteristic, it may not be the most relaiable one. A size range may be a better one. The next character to look at would be the head. In the fuzzy photo you can still see that the eyes are wide set and the head is not flattened like that of a heptageniid mayfly. Instead the head is small in proportion to the metanotum again fitting the description of the Ephemerids. The abdominal markings look to be a close fit the description of Needham, 1920, 1935, and Burks 1953 for Ephemera varia. There are no heptageniids with adult abdominal markings like this. The dark markings on the crossviens also fit the description of Ephemera varia again see Needham 1920, Needham 1935, and Burks 1953. The fore legs have the banding at the joint of the femur and tibia, again fitting the description of E. varia. And then you have the timing, which as well all know is not a great way to identify a mayfly, but in general, it's yellow drake time in PA.

As to how to tell the difference between E.. varia and E. guttulata the obvious difference in the dun statge is the overall coloring of the mayfly dorsal abdominal markings. In general, because again there is a lot of variation in the coloration of mayflies, the E. guttulata will be darker in coloration with a slight green hue in the wings and a yellow creamy coloration to the ventral side of the abdomen in the dun stage than the more lighter creamy whitish yellow of E. varia.In E. guttulata the dorsal side of the abdomen will be a dark continuous band running the whole lenght of the abdomen. In E. varia the dorsal abdominal portion of the mayfly will have a series of dark markings with a lighter medial stripe along the entire abdomen. In the spinner stage the dorsal stripe on E. guttulata is not there and the abdomen is without marking for the most part. The dorsal portion of the abdomen retains the markings of the dun stage in E. varia.


I "know" Crepuscular through the Internet. He stares at bugs through microscopes and has a tank at home to study them.

Anyway, check out the OP pic and a pic of a yellow drake spinner from Troutnut. Add to that the identification "keys" Crep mentioned along with the references he posted. You decide for yourself.

 

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Chaz wrote:
You cannot consider a flies identification without taking into account the habitat, Yellow Drakes are found only in water of the highest quality, I doubt that description fix the Breeches or Hammer Creek. They are pretty rare in PA. As to the size the drakes are big and the flies pictured are not as big as I'd expect Yellow Drakes to be.
With that in mind I still think they are cahills of some sort.

So you're saying that I haven’t collected E. varia from the breeches? Wow. I'm not sure how to take that one.

In addition to this I would be happy to have a science-based discussion on the taxonomy of an aquatic insect, there have been plenty of times when I have been wrong about determinations. I am not the end all be all on aquatic insect taxonomy (but it is my vocation). To just put it out there that someone is wrong about identification because of speculation about size, species abundance, habitat requirements and pollution tolerance seems a bit much.

I would agree that the presence of some species of mayflies in a particular stream is limited by habitat requirements, but that has nothing to do with their taxonomy. The Ephemerids are burrowing mayflies and therefore require silty areas to burrow into, both Hammer and the Breeches have plenty of that type of habitat.
As far as water quality goes, E. varia has a Hilsenhoff value of 3 the same as Ephemerella invaria. While I would agree that they like decent water I think we all know that the sulphur Ephemerella invaria is fairly ubiquitous. Also, E. varia may not be as rare as you think. In many cases however they do not occur in large numbers in most streams. Hoover 2001 (which is the most complete mayfly distribution work completed for PA)documented E. varia in 48 different streams in PA including the Yellow Breeches. Of the 48 listed creeks several are listed by DEP as impaired.


I was just trying to help answer a question.
 
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