Blue Winged Olive Dun

The Blue Winged Olive is the “universal” mayfly because it is found in just about every trout stream in the USA. Also, the hatch occurs over a much longer period of time than most of the mayfly family. In both the Eastern and the Western portions of the USA, they hatch sporadically through the year starting as early at the warmer days of winter and continuing to hatch through the fall season as well. During this time, there may be even more than one generation of the insects hatching. Most importantly to anglers is that the many species of the Blue Winged Olives make up a good deal of the trout’s diet through the year You shouldn't leave home without imitation patterns in stages of this one.

The weather and the day time temperature affects the hatches in a couple of ways. First, the hatches will slow down in the warmer months of summer and then increase in the temperature cools down. Also, when hatches occur in the cooler months, they tend to hatch during the warmest times of the day, usually around noon. As you might expect, in the warmer months, the hatches usually start occurring around mid-morning and slowing down in the late afternoon.

The Blue-Winged Olives that are found in most of the streams in the USA are of the Beatis genus of the Baetidae family of mayflies. These duns have two tails and a very tiny hind wing. There are a few species that do not have a wing whatsoever, but this is a minor variance. Since they are called blue winged olive flies, you can expect the body to be green or olive color with gray highlights. The wings are a mild blue or even could be called a shade of gray.

For more information about Mayflies please go to Class 301 Introduction to Mayflies.