Last winter Peter and I went a little crazy with the color blue. We tied lots and lots of streamers with it, nymphs with it, I even tied a couple dry flies with it. We had all kinds of blue materials in the shop on the tying wall. Some people thought we were crazy. We sure didn't.
Blue is one of those colors you don't see too much of outside of the steelhead market. Will it work for trout flies? Sure, why not. Everyone thought that purple was just a fad and a crazy color that couldn't possibly catch fish. But people tied flies in it and sure enough it stuck around. Today everyone knows about the Purple Haze. There aren't any bugs that come to mind off the top of my head that are purple. What makes it work so well?
My personal theory is that fishing colors that trout don't see all the time really makes a difference. Purple worked so well when it first came out partly because no one was fishing purple flies. If you look in fly bins at a Western trout focused shop, you likely won't see much blue. That's one of the reasons I tied a lot of flies in it.
Another reason to go with blue is it just looks "fishy". Blue flies just look great in the water. It's a color to have faith in.
Peter sent me this picture of a brown that ate one of his streamers earlier this week:
I'll be fishing blue hard this fall. Stay tuned for more.