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3. maccafertium?

found this lone mayfly amidst a hatch of light hendricksons
(e. invaria) it had 2 tails found may 27in the afternoon

where?

southeast minnesota

hmmm...i don't have my spectacles, but it could be Maccaffertium/Stenonema or perhaps Leucrocuta. what's the size of this beast?

between 14 and 16 mm or probably a size 14 hook

WITH my glasses (and the size info), you probably do have a Maccaffertium species here. The mostly dark, crowded crossveins of the wings are typical of this genus group. Anyone out there wanna venture a guess about the species ID? Check out the coloration of the abdomen and hind wing.

You know you want to!

Okay Konchu, I'll come out and play. I would like to use the clues you provided, but am unable. It is my understanding that (7) Maccaffertium species are present in Minnesota, M. exiguum, M. mediopunctatum mediopunctatum, M. mexicanum integrum, M. modestum, M. pulchellum, M. terminatum terminatum, and M. vicarium. Three or four of them can probably be eliminated based on inadeqate body length. Of those remaining, based largely on emergence date, my guess would be Maccaffertium vicarium.

Taxon,
'Dryfly' stated it seemed to be a size 14/16. Isn't E. vicarium about a size 10.
The photo of the insect looks like it has an olive tint to me.
If so, doesn't that rule out E. vicarium?
Perhaps it could be M.modestum, M.mexicanum, or M.luteum.
John

quillgordon

I mislead you when I said it was a 14 or 16, size 12 probably would have been more appropriate

thanks for your replies I was thinking vicarium also just wanted to know what you experts thought

John-



The Biology Of Mayflies lists adult body lengths as follows:

Stenonema fuscum (Maccafertium vicarium) - 10 mm
S. rivulicolum (M. vicarium) - 10 mm
S. vicarium (M. vicarium) - 12-14 mm

So, it would appear the adult body length range for M. vicarium would be (at least) 10-14 mm, which in standard dry fly hook size, would be #13 (half way between #14 and #12) to perhaps #8.

The abdomen looked like terminatum to me, but with a little book work, the size more or less rules it out (too big). Vicarium may be as close as we can get without other views of the beast. Who wants to argue? I'm game...

Dryfly-



I'd like a clarification concerning specimen length. I assume the above quote means you now believe the body length, from front of head to end of abdomen (excluding tails), to be ~12 mm, rather than between 14 and 16 mm, as you originally stated. Is that correct?

Perhaps you could measure the diameter (in mm) of the clear vial behind the specimen, and then divide by 2, as container's diameter appears to be approximately twice the body length of the specimen.

I meant a size 12 hook, so 14mm to 16mm would still be correct

Dryfly-

A standard size #12 dry fly hook would be used to imitate a specimen with a body length of 9-10 mm, not one with a body length of 14-16 mm.

Is it possible for you to measure the diameter of the clear vial that appeared behind your specimen? I believe that would result in a more accurate measure, than would estimating hook size, and then attempting to convert to mm of body length.

Konchu-

Although I am unable to resist your offer, before engaging in more fun (but probably fruitless) discussion concerning species, I'd really like to firm up the specimen body length issue with Dryfly.

Incidentally, would you agree that the specimen is (most likely) a female imago?

I measured the container and it was 46 mm wide so it would be 23 mm but probably a little less than 23. It was a male. Sorry I couldn't get any better pictures.

Dryfly-

Thanks for trying. I was thinking the container might be close enough to the specimen to not have been seriously reduced in perspective by being further away, but I am obviously mistaken.

So, reverting to the previous method of length determination, if you are convinced that it would be a hook size #12, then let's go with a body length of 9-10 mm.

I assume you concluded it was a male because it had claspers, which I was unable to see from your photo. If so, then I must also be wrong about the lifestage, as the forelegs appear way too short for it to a male imago (spinner), so it must have been a male subimago (dun).

taxon
Thanks for your tries at indentifying this mayfly. It molted into a spinner after i took the pictures. It had claspers. My informaton is probably too vague to narrow it down too species. oh well