Motrout, if BWOs are what you are seeing, man, fish BWO imitations. I have honestly never run across them, at least not that I couldn't imitate with whatever I had on hand. I've never fished a Trico hatch either, or many of the other hatches so many have described on this site. On the two streams for which I have the most trout fly fishing experience - the Rifle and the Maple in northern lower MI - the big hatches are Light Hendricksons (probably still going on right now), Light Cahills, Hexagenia (not found in the Rifle), and various caddisflies. And, grasshoppers during the summer in the tributaries and areas near grassy banks. When there are no hatches, it's time to get out the Royal patterns - Coachman, Wulff, Parachute, etc.
Fish what you see and what works best for you and what you have the most confidence in. And yes, I am rather on the opinionated side, but I try to relate only my opinions and what I can say from my own experiences and not tell anyone else what they should do, only what I would do given the circumstances. And, what works for me in the waters I fish. As I like to say, your results may differ...
Go say HI to Crane creek for me and hassle a few of those McClouds. Did I tell you I caught the largest hornyhead chub of my life in there as well? He went for the nymph - yes, I actually used one, sight fishing so I saw him take it - when the rainbows turned up their noses at it...And he put up a pretty darned good fight for a chub! Big male with a red spot behind his eye and turbercules all over his forehead...
Jonathon
No matter how big the one you just caught is, there's always a bigger one out there somewhere...