This species shares its distribution with the much more common Acentrella turbida over much of it's range. In the West, it overshadows turbida in some locales. It can be differentiated from turbida by the presence of hind wings and from most other baetids by its hind wings having two longitudinal veins (Longitudinal vein: Longitudinal veins are the major long veins running length-wise through an insect's wing, connecting the base to the outer margin, or the major branches from those veins.) and a lack of costal projection (
» Species insignificans (Tiny Blue-Winged Olive)
Costal projection: A bump or point sticking up from the front margin of an insect's wing, usually the rear wing of certain mayflies. It is sometimes called a costal process.). It was previously classified as Baetis insignificans.
The costal projection of a Baetidae
Pictures of 2 Mayfly Specimens in the Species Acentrella insignificans:
Male Acentrella insignificans (Tiny Blue-Winged Olive) Mayfly Dun
View 11 PicturesThis specimen emerged indoors from nymphs I had collected, then partly molted into a spinner but got stuck along the way. I've included a couple pictures showing some of the spinner colors. It got a bit waterlogged after emerging, so the wings aren't in perfect shape, but it still represents one of two Baetids that were emerging and drawing trout to rise on the Yakima. Based on body size and shape, it is most likely the same species as this nymph.
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