Bug hatch MF Snoqualmie - what is it?

I fished the MF Snoqualmie yesterday (Friday the 27th) and had a nice day catching small cuts. Caught them on top on caddis and an ant, caught more underneath on a PT.

We moved to a new spot around 6:30 or so, and a large bug started hatching, swarming the air. They have a body color somewhere between cinnamon and brown, about 1/2" long, upright wings, and a long (1") forked tail. Can anyone tell me what this bug is?

On a side note to this, the fish weren't coming to eat the adults or dead spinners, but I believe this is because two fisherman had just pounded the area pretty hard.

I'm attaching photos (I hope). Thanks, all!

March brown I believe...

Looks like its in the Heptageniidae family of mayflies, probably an Epeorus. Not sure of the common name though.

It's not a March Brown because the wings in the picture are almost completely transparent. March Browns' wings are so distinctive: speckled with brownish-black stryations.

When I first saw it, I also thought Epeorus. However the color of the body is wrong for it to be a yellow quill, Epeorus' common name.

It could be a PED; although that would definitely be a much bigger version than the ones I'm used to seeing.

My guess it's a Ephemera simulans- a type of brown drake. It's certainly the right time of year for it, the right size, and that section of the Snoq seems to have the right habitat for it: lots of gravel/sandy bottoms with cold, medium-fast flowing water. If the hatch did occur at 6pm+ that would also be about the right time for it too.

Did they have 3 tails and was it a slower stretch of river?

Two very distinct, long tails. The stretch had both a deep "slower" pool and that flowed over into a fast section. The bugs were hovering (flying, mating, etc) over the whole section.

And to validate what Cap'n Awesome said, the bug does have transparent upright wings. The bug flies head up, tail down.

UPDATE: I just did a google on Brown Drake, and there's a great picture here: http://www.flymartonline.com/content24.html. Although the color of the bug in this picture is gray, it looks the same bug. However, this appears to have 3 tails, not two. I found another pic up at Worley Bugger site and that Brown Drake has 2 tails. That's probably what it is.

I was on the Southfork, Friday evening and the one bug I noticed most were the big black flying ants! If I were to go back I would sure take a few big ant imitations.
Didn't catch anything myself but there was a huge hatch of bugs that looked a lot like the ones you saw but by then it was getting really dark.

LB

Boy, it's tough to argue with Taxon, and only half because he uses those tough-to-pronounce words! Thanks for the ID.

I did a bit more looking around on the net and found another photo of a Brown Drake. Looks like they have 3 tails, not 2. (http://www.troutnut.com/naturals/mayflies/ephemera/Ephemera_12_1.jpg)

Thanks for all the input folks!

It looks to me as if it originally had 3 tails, the right tail broke off.

We saw tons of these flying around right in front of us and distinctly saw only 2 tails. Not being an entomologist, maybe there are different ... families? ... that have 2 or 3 tails?

Thanks for the recommendation - I'm definately going to check it out!

I just read this thread and I couldn't tell if y'all settled on an ID for the bug. If it helps or is of interest to anyone, I saw some pretty significant hatches of what I would say is the exact same mayfly on the St. Regis river in Montana this past weekend. They were the same color - quite large with a split tail (2) about as long as the body and clear wings. Interestingly, the fish seemed to completely ignore the adults and spinners. I didn't bother taking any pictures as I was focusing on getting myself good and skunked at the time. For the record, I did manage a few fish - one 20" brown that came to a streamer after I gave up on the dries.

Well seeing as how someone else bumped this post I'll add a few comments. I too fished through a hatch of this bug on the MF Snoquolmie. At one point I could look downstream through the falling sunlight and see at least a few thousand of these filling the air. I happened to have a near exact match in my fly box (although the tails were much longer) so naturally I tied it on. I got skunked and noted that I did not see a single rise to these guys. I kept asking myself - If the fish aren't eating the real McCoy, why would they go after my imitation? Should I be fishing subsurface emerger variety of something similar (not that I am smart enough to know what it would look like)? I tried some nymphs but in the end was spanked.

What do you do in the situation where you know fish exist but are completely ignoring (on the surface) a hatch?

Of course, I had fun anyway. Felt like mid July last Saturday.

I'm sure I saw the exact same fly on Rattlesnake lake last Sat. I just happened to see one adult dead on the water, but it looked stillborn as it still had the clear upright wings. I noted the 2 tails and the "quilled" looking segmented dark brown/red body. I only saw the one fly not a hatch. Interestingly the only "dry fly" I had any luck at all with (the water was really choppy) was a dark red brown softhackle wet fly fished in the film. Everytime I could get it near a rise form, I had a strike, but not on anything else. I wonder if for whatever reason trout only like the emergers of this species. Of course it's impossible to say as there wasn't a significant hatch of this critter.....

Hey, Jim. Interesting that you didn't see or get a fish when you went. Was it the same Friday or the Saturday after?

As I mentioned, my thinking was that some other fisherman had flogged the area, but that may not be the case. If I hadn't seen the two dudes down below, I may have tied on a PT or Hares Ear. Other that that, I have no guess what the fish would come for.

Its a spinner, probably Epeorus. They hatch pretty heavily in North Idaho and Western Montana this time of year. Epeorus albertae is common and is often mistakenly called a pmd, or even a green drake (see previous report on the Coeur d'Alene River.) The duns do vary in color from yellow to olive, but the spinners have rusty bodies with hyaline wings.

Also, I think the wide/flat head suggests that this mayfly belongs to the "clinger" category, which includes Epeorus.