Continuing our series on BWO basics….

BWOs are one of the mayflies that swim – they’re slender and propel themselves by flipping their tails.  They typically inhabit slow to moderate water flow areas, though you will see some in riffle areas.  BWO nymphs sometimes drift in the current (mostly at sunrise and sunset) seeking new places to park and eat. 

Like most aquatic insects, when the nymphs mature they rise to the surface, split their skin (like almost all mayflies), and the winged dun emerges or crawls out, resting briefly on the surface and drying their wings, and then they fly off.  You know the rest of the story – they mature into spinners, mate, and the females return to deposit eggs.  I know - yawn. 

Interestingly the BWO duns are smaller flies, in the 18-22 range for most of them, with body colors including gray, olive, olive gray and medium brown.  Wings are dun colored (a smoky, translucent blue); the nymphs are dark brown and slender for the most part. 

More BWO stuff to come….

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Tags: Bugs: Mayflies - BWO