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The
 hatches of these small mayflies occur on virtually all Western
streams and are an important food item for the Yakima River trout. The
Blue Wing Olive (B.W.O.).
begin emerging during the month of February
and will continue well through the month of May on the Yakima.
These important little food items will make their return
once again in the fall months of October and November and can even be
seen at times throughout the winter months of December and January. |
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The hatch usually
will begin around 11:00 a.m. and can last well
into dusk, depending on the time of year it happens to be. The
best emergence
and trout feeding opportunities will occur during
the cloudy days of spring and late fall. The life cycle of this little mayfly is quite extraordinary. One
generation hatches in the spring and lays its eggs into the water. The nymphs grow
feeding on algae and vegetation and emerge once again in the fall, starting the cycle over
again before winter.
The Yakima river's fall emergence of Baetis, tends to be quite smaller in size compared to the spring emergence with sizes ranging in from #16-22. In spring, you will find sizes ranging from #14-18. Because the nymphs are tiny they have trouble breaking the surface of the water. Once the hatch begins the duns fly to the bank where they remain until there metamorphosis to the spinner stage. You will see the spinners in the late afternoon or evening depositing there eggs on the surface on the water. |
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Blue Wing Olives are a three-tailed mayfly with a brownish-olive body and light dun wings, hence the name Blue Wing Olive.
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| Yakima River B.W.O. Video Footage |
