I generally use Byron's thought process on my biot bodies. I like the smooth for any fly that will remotely resemble the dun or spinner profile, even later stage emergers. Most of the Mayfly hatches I fish regularly are those with pretty slender and sleek bodies. If a fish is looking for a dun profile, the ridges being out can add some bulk to the profile that I do think will turn off a selective fish. In general though I don't think it always matters. I have tied this first fly with the ridge up and used it without noticing much of a difference in it's ability to catch fish. But you never know when you will run up against that big selective bank feeder.
Definately an emerger, nothing dunlike on this fly so I like to tie it in with the ridge out to give a little added texture to the fly.
Reply With Quote