Blue-winged Olives
Baetis
Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
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This is a striking caddis larva with an interesting color pattern on the head. Here are some characteristics I was able to see under the microscope, but could not easily expose for a picture:
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
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Crepuscular on Apr 4, 2012April 4th, 2012, 12:47 pm EDT
I collected all of these from the same rock. The nymph on the right might be Epeorus fragilis. Close ups are all of the one on the right
Entoman on Apr 4, 2012April 4th, 2012, 1:35 pm EDT
Wow, You have a cornucopia there!:)
The four on the left look to be vitreus. The big boy in the center is pleuralis? The far right one and the little guy below and to the left are probably fragilis. Based on the substantially different levels of development, I have my concerns whether they are the same species though. Could one be the very similar appearing frisoni? I don't think the latter has been recorded for PA - yet. When I get home this evening, I'll look into it.
The four on the left look to be vitreus. The big boy in the center is pleuralis? The far right one and the little guy below and to the left are probably fragilis. Based on the substantially different levels of development, I have my concerns whether they are the same species though. Could one be the very similar appearing frisoni? I don't think the latter has been recorded for PA - yet. When I get home this evening, I'll look into it.
"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
Falsifly on Apr 4, 2012April 4th, 2012, 1:54 pm EDT
Wow, You have a cornucopia there!:)
So Kurt, which one is the cornucopia? Just curious, I want to stay on top of things.:)
Eric, were those taken with a new camera?
Falsifly
When asked what I just caught that monster on I showed him. He put on his magnifiers and said, "I can't believe they can see that."
When asked what I just caught that monster on I showed him. He put on his magnifiers and said, "I can't believe they can see that."
Crepuscular on Apr 4, 2012April 4th, 2012, 2:21 pm EDT
No new camera yet. Taken through my scope.
Entoman on Apr 4, 2012April 4th, 2012, 6:27 pm EDT
Just curious, I want to stay on top of things.:)
No problem, Al. I was excitedly referring to the very rare E. cornucopia and forgot to italicize. It's the one in the photo...:)
Eric - Are you able to look at their femoral flanges and gills from the first segments? Also, what about punctatus as a possibility in this mix? The four on the left I'd break into two groups and look closer at them. The top ones are marked a little differently from the bottom two.
"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
Crepuscular on Apr 4, 2012April 4th, 2012, 7:28 pm EDT
Eric - Are you able to look at their femoral flanges and gills from the first segments? Also, what about punctatus as a possibility in this mix? The four on the left I'd break into two groups and look closer at them. The top ones are marked a little differently from the bottom two.
Well I won't be back in the office until Monday so it will have to wait until then to get some more photos. What exactly are you looking for? Gills on seg 1 are elongated. I was really relying on the head capsule outer margin with abrupt transition near outer anterior corners of compound eyes which is one character that separates fragilis from frisoni in Burian 2008.
But punctatus isn't even included in that key.
As far as the E. vitreus on the left in the photo I'm pretty sure they are all the same but I'll have to take a closer look. They've been pickled for a week so some may have faded etc.
Jesse on Apr 4, 2012April 4th, 2012, 7:47 pm EDT
They are some really great shots!
Most of us fish our whole lives..not knowing its not the fish that we are after.
http://www.filingoflyfishing.com
http://www.filingoflyfishing.com
Entoman on Apr 4, 2012April 4th, 2012, 9:35 pm EDT
I was asking about the femoral flanges and gills of all the specimens. What I'm looking for is whether the flanges are blunt or pointed. As far as the gills, whether they are elongate or not and whether the sclerotized strip is angled at about 45 or 90° is also helpful. A ventral of the posterolateral spines is useful for the same reason.
That would be diagnostic if this were a New England male. The lack of concavity of the mesonotum bothers me not a little, too.
I was really relying on the head capsule outer margin with abrupt transition near outer anterior corners of compound eyes which is one character that separates fragilis from frisoni
That would be diagnostic if this were a New England male. The lack of concavity of the mesonotum bothers me not a little, too.
"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
Konchu on Apr 5, 2012April 5th, 2012, 5:09 am EDT
Epeorus frisoni probably has a very restricted range of geographic distribution, so be cautious.
Entoman on Apr 5, 2012April 5th, 2012, 11:55 am EDT
You are right, Luke. I understand that frisoni is a larger species found at higher elevations further North. Just looking to eliminate the possibilities by means other than distribution, if possible. The size difference between the far right specimen and the little one below it is interesting. Isn't size one way to discriminate between the two species? Can there be this much size discrepancy within the species at this time of year?
The four on the left also intrigue me. At first I thought they were just variations of the same species, but look at the terga. The upper two specimens are marked identically and the bottom two are marked identically.
The four on the left also intrigue me. At first I thought they were just variations of the same species, but look at the terga. The upper two specimens are marked identically and the bottom two are marked identically.
"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
Crepuscular on Apr 5, 2012April 5th, 2012, 5:26 pm EDT
What's a matter Kurt? Three species from the same rock isn't enough for you? ;).I would not be surprised to see a difference in size. How about male vs female? The E. vitreus on the left are different sizes no? All of the head capsules look the same. 
Falsifly on Apr 5, 2012April 5th, 2012, 5:51 pm EDT
The size difference between the far right specimen and the little one below it is interesting. Isn't size one way to discriminate between the two species? Can there be this much size discrepancy within the species at this time of year?
But notice the difference in wing pad development, couldn't this just be a difference in instar?
Falsifly
When asked what I just caught that monster on I showed him. He put on his magnifiers and said, "I can't believe they can see that."
When asked what I just caught that monster on I showed him. He put on his magnifiers and said, "I can't believe they can see that."
Entoman on Apr 5, 2012April 5th, 2012, 6:51 pm EDT
Eric -
A triple is nice, but maybe you hit a home run!:)
Yes. That is confirmed now with your latest photo. The fascinating thing is there are two with dark tergal rectangles in both sizes and two with dark triangles in both sizes. I assumed it's because you have both male and female represented (one in each size which is cool), but couldn't quite make out their entire heads to know for sure.
Al -
Yes. That's correct. What is interesting though is how far behind. Unless it's a different species, its hatches must trickle off in very low numbers over a long period, even if the nymphs are abdundant.
BTW - Thank you both for confirming my original calls with such conviction. I'll stop second guessing myself now... See how I cover my bases?:)
A triple is nice, but maybe you hit a home run!:)
The E. vitreus on the left are different sizes no? All of the head capsules look the same.
Yes. That is confirmed now with your latest photo. The fascinating thing is there are two with dark tergal rectangles in both sizes and two with dark triangles in both sizes. I assumed it's because you have both male and female represented (one in each size which is cool), but couldn't quite make out their entire heads to know for sure.
Al -
But notice the difference in wing pad development, couldn't this just be a difference in instar?
Yes. That's correct. What is interesting though is how far behind. Unless it's a different species, its hatches must trickle off in very low numbers over a long period, even if the nymphs are abdundant.
BTW - Thank you both for confirming my original calls with such conviction. I'll stop second guessing myself now... See how I cover my bases?:)
"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
Crepuscular on Apr 5, 2012April 5th, 2012, 8:17 pm EDT
I still want to be sure that it's E. fragilis. I sent some photos to D. Funk at Stroud but haven't heard back. He said he has never collected it in PA. I have two others I'd like to talk to about it. Luke what do you think? I'd like to hear Gonzo's opinion as well.
Entoman on Apr 5, 2012April 5th, 2012, 9:42 pm EDT
Eric -
Me too. Though, I'm reasonably confident in fragilis.
Maybe he hasn't, but others have. The species is reported from PA.
Luke what do you think? I'd like to hear Gonzo's opinion as well.
Me too. Though, I'm reasonably confident in fragilis.
I still want to be sure that it's E. fragilis. I sent some photos to D. Funk at Stroud but haven't heard back. He said he has never collected it in PA.
Maybe he hasn't, but others have. The species is reported from PA.
"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
Konchu on Apr 6, 2012April 6th, 2012, 4:01 pm EDT
When were these collected? How big?
Crepuscular on Apr 7, 2012April 7th, 2012, 10:44 am EDT
Luke they were collected March 30th. The E. fragilis is about 9mm.
Entoman on Apr 7, 2012April 7th, 2012, 11:04 am EDT
Isn't that way too big for fragilis? Even the matures are supposed to be well under 7mm. This new info shoots a big hole in my previously expressed confidence.:)
Not to throw more cold water on our attempts, but...
A closer look at the abdomen does show paired tergal spots.
Not to throw more cold water on our attempts, but...
Burian, et. al. - 2008
After studying the New England subset of the eastern Nearctic species of Epeorus, it is now clear that there is much unexplored variation within and among species. Many of the characters studied for larvae and adults of E. frisoni are subtle and some are within the range of variation for E. fragilis and E. pleuralis (emph. mine)... This suggests that at least some larval characters presented here as "diagnostic" may need to be modified as more material becomes available for study.
A closer look at the abdomen does show paired tergal spots.
"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
Crepuscular on Apr 7, 2012April 7th, 2012, 12:18 pm EDT
Maybe I'm wrong abouth the length. I am going from memory. Mine is not very good. We may need to table this until Monday. When I can look at it again. I will try an collect some more specimens as well.
Entoman on Apr 7, 2012April 7th, 2012, 12:58 pm EDT
Sounds good.
"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
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