I was going to share my belief that this specimen is E. aurivillii, but I see you beat me to it.:) Oh well, with all the "fast gun" Bugmeisters on this site, there are really only two types, "the quick and the dead!":)
This species is fairly common in the West, but nobody seems to know what the duns look like. If you could catch some ripe nymphs this spring and hatch them into duns, it would be excellent reportage.