Big Mayfly needs ID...Taxon?

Observed this large specimen crawling on the side of the house this evening.
Based on initial inspection and the general coloration, I thought it might be the same species
as one that I photographed a few years ago and Taxon ID'd as a Brown Dun:

http://www.washingtonflyfishing.com/gallery/showphoto.php?photo=11862&ppuser=5427

But in looking at the photos side by side, they're clearly different bugs. Plus, this one was about twice
the size of the Brown Dun from before (a good 3/4" from head to butt, not counting the tails).

Perhaps Roger or someone else can weigh in with a positive identification.

Whatever happened to the innocent days when a bug was just a bug?
Now everything is viewed as trout food.

Itchy -
Until Roger pipes in and proves me wrong, I'm going to say it looks like a March Brown dun (Rithrogenia, maybe R. morrisonii). The two tails, main wings with a darkish section near the leading edge caused by the closely dividing veins, and the eyes set on tip of a broad head so that they almost look like they are staring straight up, instead of ahead are what I think make the case for Rithrogenia.

Thanks to Hafele and Hughes "Western Mayfly Hatches" for any insight I have to offer.
Dick

Come on...that's a Bacon Fly if I've every seen one....
Check your books. Most popular mayfly pattern in the US.

Just as I said.... baconfly.....also known as an Ameletus female subimago, like Tax said.......

Most impressive, Roger. Thanks. Don't see many mayflies where our house is...must've blown in on yesterday's wind from a body of water where it hatched...? Other than a seasonal creek (trickle) here or there, the nearest moving water is the Snoqualmie, which is about a mile by way of the crow (or mayfly). There's some standing water in a marsh about a 1/2 mile by way of the same crow/mayfly. Would a marsh produce these?

Must admit, bacon sounds good right about now.

Thanks again, Roger. Interesting would it be to know how it got here and from whence it came.