Giant Mayfly

[iliketofish]

I'm by no means an expert on Mayfly identification, but today I encountered a real monster and I don't know what it is. they were just sitting on the outside wall of a building in Idaho Falls this morning. I tried to figure it out and I think it might be a Hexagenia, but if anybody else knows better I'd appreciate some feedback. The picture isn't the best but it's a start. The mayfly is 24 mm long without the tails (there were 2 by the way), and yellow and brown in color.
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[tob04002]

I got caught in a hatch that fits that description on the Teton River about a month ago.

Josh
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[packfish]

It is the hex hatch- down town IF has one. The silt there before the dam provides a great breeding ground. This hatch shuts down Lake Eire for fishing for a week or so. The mats of schucks on the water are often well over a mile wide and long. At times they have to bring in snow plows to scrape them off the bridge pavements because squished it's like driving on an oil slick. This years hatch on Lake Eire happened all at once over the entire Lake. I have a bro that's a guide on the Lake and he was having to make runs up past Detroit to put his clients into fish. -
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[prontotp]

I was on the teton river last week fly fishing for the 3rd time ever and right at dark a hatch came on with flies that big but a slightly different body color. the fish were going crazy all over the river and my more experienced friend/guide said that he had never experienced a hex hatch before but he was really excited.
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[packfish]

Possibly like this ???

[url "http://www.google.com/imgres?imgurl=http://www.troutnut.com/im_regspec/picture_3801_small.jpg&imgrefurl=http://www.troutnut.com/common-name/19/Green-Drakes&h=290&w=244&sz=52&tbnid=yGNEAngx0dkkiM:&tbnh=115&tbnw=97&prev=/images%3Fq%3Dpicture%2Bof%2Ba%2Bgreen%2Bdrake&hl=en&usg=__0U4jXrNjA5QBbmKiuL2W1UgDqGo=&ei=VDlvSpT2LYyMMvz1hOMI&sa=X&oi=image_result&resnum=2&ct=image"][/url]
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[iliketofish]

Thanks packfish. That's what I thought, but I wasn't sure because most of the info I found on the internet said that big ones like that aren't supposed to be this far west, but now I know.
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