You can use this pattern in nearly every season. The Blue Wing Olive mirrors the callibaetis dun hatch, which usually occurs during wet and nasty weather. The duller color won't spook fish feeding on the top on thhese gray days. Per 12. Sizes: 16, 18, 20.
Great fly for the price. Note: This lot of blue wing olives and adams hooks were tempered too hard. Hook will break when trying to crimp down barb. I have bought a lot of Cabelas bulk flies in the past with no issues.