The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
Size - (excluding tails) - 12 mm
Status at time of photo - preserved, but photographed within days of capture.
W. C. Day, Aquatic Insects of California differentiates morrisoni nymphs by submedian pale dots on tergites 8 & 9, which look to be in evidence. This is one of the "super-hatches" on this river that can be prolific March through April.
This mayfly was collected from the Lower Yuba River in California on March 3rd, 2011 and added to Troutnut.com by Entoman on November 1st, 2011.