Blue Wing Olive (BWO) hatches often bring out selective trout, especially on pressured rivers and tailwaters. Matching size, profile, and presentation is usually the difference between refusals and eats. Most BWO fishing happens in sizes 16–20, with emergers outfishing dries when trout are feeding subtly in the film. Target softer seams, eddies, and slower edges during active hatches.
BWO hatches peak in spring and fall and are strongest during overcast or rainy weather. These mayflies can hatch multiple times a year and often produce longer, more consistent windows than other mayflies.
Trout key in on specific stages of the insect, so adjust your flies as their behavior shifts. Use dries when fish are rising confidently, switch to RS2s or emergers during subtle sips, and downsize if fish are refusing your presentation.