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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
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.

Dorsal view of a Ephemerella mucronata (Ephemerellidae) Mayfly Nymph from the Yakima River in Washington
This is an interesting one. Following the keys in Merritt R.W., Cummins, K.W., and Berg, M.B. (2019) and Jacobus et al. (2014), it keys clearly to Ephemerella. Jacobus et al provide a key to species, but some of the characteristics are tricky to interpret without illustrations. If I didn't make any mistakes, this one keys to Ephemerella mucronata, which has not previously been reported any closer to here than Montana and Alberta. The main character seems to fit well: "Abdominal terga with prominent, paired, subparallel, spiculate ridges." Several illustrations or descriptions of this holarctic species from the US and Europe seem to match, including the body length, tarsal claws and denticles, labial palp, and gill shapes. These sources include including Richard Allen's original description of this species in North America under the now-defunct name E. moffatae in Allen RK (1977) and the figures in this description of the species in Italy.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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DayTripper has attached these 4 pictures to aid in identification. The message is below.
Additional baetis pic
DayTripper
DayTripper's profile picture
Northern MI

Posts: 70
DayTripper on May 10, 2013May 10th, 2013, 5:38 pm EDT
The subimago is a male, unfortunately I lost my ruler before I could get a measurement on him. Aren't clear rulers great?! It was collected on 4/27/13 in northern MI.

The imago was collected on 5/8/13 in northern MI. It molted into a spinner on the way home.

I believe the nymph is the same species as the subimago as it was collected at the same time as the subimago. On that particular day, you couldn't pull the seine out of the water without pulling in a few dozen of these at a time.

As always, thanks for any insight!
Oldredbarn
Oldredbarn's profile picture
Novi, MI

Posts: 2600
Oldredbarn on May 10, 2013May 10th, 2013, 6:42 pm EDT
Alex...I think you have a couple different bugs there...The first is a Baetis, probably tricaudatus.

The second one could be P adoptiva. The Little Mahogany.

The nymph...E invaria...The Light Henny.

How's that for a guess?

Spence
"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively

"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood
DayTripper
DayTripper's profile picture
Northern MI

Posts: 70
DayTripper on May 10, 2013May 10th, 2013, 7:33 pm EDT
Thanks guys! I really appreciate it!
Oldredbarn
Oldredbarn's profile picture
Novi, MI

Posts: 2600
Oldredbarn on May 10, 2013May 10th, 2013, 7:57 pm EDT
I just to a peak at #2 enlarged it has the small hind wing of baetis and the head looks like the one in my past post. Making it the same as the 1 rst one but female.



She has three tails Mack...Baetis only 2. Baetis, like its cousin Plauditus don't have hind wings. It is Paraleptophlebia adoptiva...

Spence
"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively

"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood
Oldredbarn
Oldredbarn's profile picture
Novi, MI

Posts: 2600
Oldredbarn on May 11, 2013May 11th, 2013, 3:09 am EDT
Mack...I'm looking with an iPhone. Not the best method for this, maybe i should move to a bigger computer. In the earlier post you said you had blown it up and there was a hind wing. If there isn't a hind wing and it only has two tails instead of three I stand corrected and it could be a Baetis female.
"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively

"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood
Crepuscular
Crepuscular's profile picture
Boiling Springs, PA

Posts: 920
Crepuscular on May 11, 2013May 11th, 2013, 5:48 am EDT

Baetis, like its cousin Plauditus don't have hind wings. It is Paraleptophlebia adoptiva...

Spence


Baetis do have small hind wings. http://www.troutnut.com/fullsize/picture-im_regspec/2848

I'm pretty sure it's not Paraleptophlebia. Looks like a female Baetis tricaudatus imago to me. The hind wing is hard to see but it appears to be there, and it looks like it has two tails, again difficult to see.

The nymph is definitely an Ephemerellid. You guys are braver than I to go past that.
Entoman
Entoman's profile picture
Northern CA & ID

Posts: 2604
Entoman on May 11, 2013May 11th, 2013, 8:30 am EDT
I'm with Eric on the adults. Probably B. tricaudatus. The photo of the female did give me pause, though. Sure looks like it has three tails at first glance. Baetid hind wings (on those that have them) are usually very tiny and lay horizontally. This causes them to go unnoticed to the unaided angler's eye. The perpendicular ovals of the leptophlebiids are hard to miss. I believe that is what Spence was referring to.

I also agree with Spence on the nymph. It looks like a fairly typical E. invaria imature.
"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
Oldredbarn
Oldredbarn's profile picture
Novi, MI

Posts: 2600
Oldredbarn on May 11, 2013May 11th, 2013, 2:20 pm EDT
Yep. I stand corrected...things are pretty serious when we can pull Eric from maybe the only softball game his daughter has won this year...My stats maybe off here. :)

I went back to Leonard and yes the Michigan B tricaudatus has a hind wing. Ann Miller has a typo then in her book since she claims no hind wing. It could be a problem since she lumps her discussion on Baetis and Plauditus together.
"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively

"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood
DayTripper
DayTripper's profile picture
Northern MI

Posts: 70
DayTripper on May 11, 2013May 11th, 2013, 4:17 pm EDT
Ok, I have some other photos of this spinner and went back to see if I had one that showed the hind wing a little better, and the number of tails. This one definitely had two tails and a hind wing. The additional pic is now attached to the original post. Thanks for the help in ID'ing these guys!
Crepuscular
Crepuscular's profile picture
Boiling Springs, PA

Posts: 920
Crepuscular on May 11, 2013May 11th, 2013, 4:23 pm EDT
Yep. I stand corrected...things are pretty serious when we can pull Eric from maybe the only softball game his daughter has won this year...My stats maybe off here. :)


Yes your stats are a little off (not very far off though)...it's a "rebuilding" year.

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