"Conan The Librarian" wrote

The bad news is that the hatches at that time of year appear to be
mostly #18 and #20 BWO's

BAD news?? Baetis are one of God's greatest creations G This is
especially true if you like going blind young, and freezing fingers.
I may drive all the way to Dillon for a couple weeks in April just to suffer
at their hand.

I've been trying to figure out digital macro and I'm not pleased with my
progress, but you gave me an excuse to go try a few more shots.

I pulled some of my favorite BWO ties out of my baetis box, several
individuals have been used so aren't pristine. Clockwise from top, sparkle
dun ( the body of this fly is damn close to 'right color' for the early
season baetis where I fish, a gray with olive overtones ), turkey flat
parachute (I actually prefer thorax ties, but didn't seem to have any left,
except one very beat up one ), spinner ( don't hesitate to fish as a wet),
CDC bubble back emerger, knockdowned dun ( this is a crappy individual,
turkey flat or other dark gray wing is better, I recently found some dark
gray organza and I'm going to try it hoping the dark will provide proper
outline and the added sparkle will simulate the meniscus sparkle caused by
the fluttering trapped wing. But knocked down adults are very common in the
nasty baetis weather and knocked down duns are a good pattern to carry, just
tie them better than the example), nymphy thingy ( PT nymphs work great, for
baetis I like the copper thorax ones), CDC zelon emerger RS-2like dealie,
and a nymph. Everything is an #18, 19, or 20

After looking at the photo, I could have done a better job of choosing, but
I'm too lazy to go back and try right now G

http://www.kimshew.com/BFP/twobits.jpg