Baetis or Blue Wing Olive Mayflies hatch both in the spring and fall on many waters. They are a critical food sorce and nearly all the fish in the river will key on them. The hatches are exciting to fish, especially if you have the right fly pattern. At these times the Blue Wing Olive, Emerger, RS2, Olive Body, Dun Wing is a fly you should not be without. This is a fly that can truly be the difference between a day of only talking about the scenery or actually moving some fish. When the fish are selective we trail this pattern behind a dry fly and it is equally effective when using other nymphing techniques.