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.