Though having a national distribution, this species is considered by angling authorities to be important only in the West. In localized waters where it is abundant, it can be a significant hatch. Where & WhenRegion: West
» Species margarita (Little Western Blue-Winged Olive)
Time Of Year (?): August
Time Of Day (?):Fred Arbona in Mayflies, the Angler, and the Trout says that trout prefer nymphs on the surface when the margaritas are hatching, so a floating nymph is the ideal tactic. He also says this hatch is unusually prone to producing stillborn (Stillborn: In fly fishing, a stillborn insect is one which got stuck in its nymphal or pupal shuck during emergence and floats helplessly on the surface instead of flying away. It is a specific class of cripple, although it is sometimes used interchangeably with that term.) and crippled duns.
However, Knopp and Cormier say that this species, like Attenella attenuata, emerges on the bottom of the stream and rises to the surface as a dun. This conflicts with Arbona's observation.
It may be that the nymphs of this species make several failed trips to the surface, like most in the family Ephemerellidae do, before deciding to emerge, and that Arbona observed feeding during this behavior. Or there may be a wider range of emergence behavior during this hatch than either author realized.Spinner BehaviorTime Of Day: Late dusk
Nymph BiologyCurrent Speed: Slow
Environmental Tolerance: Best in consistently cold water
Pictures of 2 Mayfly Specimens in the Species Attenella margarita:
Attenella margarita (Little Western Blue-Winged Olive) Mayfly Nymph
View 7 PicturesNotes from the microscope on the ID: Maxillary palp (
Palp: A long, thin, often segmented appendage which can protrude from certain insect mouth parts such as the maxillae. Also known as the < />palpus.) is present, distinctly 2-segmented, but very small. Gills on segment 4-7. This specimen has some unfortunate damage to the abdomen, but it's the only one I found in my sample.
The palp on the maxilla of an Ephemerella
nymph (detached and photographed under a microscope) is highlighted in red here.
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