Help & opinions here

[Byron haugh]

I now you did not solicit a pattern, but I think one of these might do?

[Rocketfish]

http://www.hatchesmagazine.com/page/january2006/86

My guess is some type of the Maccaffertium.

Wing mottling and number of tails would be wrong for Epeorus.

Isn't it mid-fall in Argentina? Are there any flies here outside of the various small types of BWO's that hatch in the fall?

Steven...thanks. And I don't know, I mean I am m not in Patagonia at this time (trout region) but near Buenos Aires. So I'm not fishing; the mayfly appeared at home. I also checked March Browns in this area. Bigger and darker than this relatively pale mayfly. Yes, it's beginning of fall.
However, I think it is very interesting to compare the bugs (in this case a mayfly) that you have in the North America with our insects and see (if any) the differences.
This one is very usual in Patagonian lakesMayfly Traful.jpg.

[Greg H]

I have a few books with pictures of bugs, but I alway check Troutnut.com when these questions appear online.
http://www.troutnut.com/hatch/589/Ma...a-Light-Cahill

[Byron haugh]

Could also be a female Calibaetis:

[Steven]

The fly in post 12 has very obvious hind wings.

[Byron haugh]

It was from a lake and the calibaetis like lakes. Although less pronounced from one picture, the Calibaetis does have hind wings.

[Steven]

Believe me, if the answer on Jeopardy was "this may fly has speckled wings and lives in lakes," my answer would be "What is a Callibaetis?"
But the Callibaetis has minute hind wings as in your picture, not large obvious hind wings as in Rocketfish's picture. Also, burrowing may flies live in lakes as well (Mackinac Island on Michigan's UP is covered in Hex and Brown Drakes in July from the hatches on Lake Michigan).

Rocketfish's pictures might be of genera we don't have here. That said, I'd go with a classic March Brown but substitute teal for the wing.

[Byron haugh]

Steven,
I was just trying to help identify the bug for the guy. My first guess was a March Brown. Then, he posted the second pic. Which mentioned a lake as the source....another clue.
So, we had: 2 tails, somewhat speckled, and perhaps from a lake (slow water).

If it is from Argentina, it may not correspond directly to the insects here. So, perhaps it might be in the family....

In addition, the first pic. Posted did not appear, to me, to have a large hind wing..

[Steven]

I think those are two different bugs.

[Rocketfish]

I think those are two different bugs.

Yes Steven, are two different bugs as I pointed.
My question was about the first one. It seems some pale mayfly, very different to the second one which is a Patagonian mayfly, 1,000 miles (South) from the first one.
So my main doubt was if you have the same (first) mayfly in US and in that case, what is it (scientifically) in your records.
Good luck.
RF