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Mayfly Genus Baetis (Blue-Winged Olives)

Taxonomic Navigation -?-
Species in BaetisNumber of SpecimensNumber of Pictures
Baetis bicaudatusBWO15
Baetis brunneicolorBlue-Winged Rusty Dun00
Baetis flavistrigaBWO314
Baetis intercalarisSmall Eastern Blue-Winged Olive00
Baetis magnusIron Blue Quill00
Baetis tricaudatusBlue-Winged Olive968

17 species aren't included.
Common Names
Pictures Below

This is page 4 of specimens of Baetis. Visit the main Baetis page for:

  • The behavior and habitat of Baetis.

Pictures of 32 Mayfly Specimens in the Genus Baetis:

Specimen Page:1234
Female Baetis tricaudatus (Blue-Winged Olive) Mayfly DunFemale Baetis tricaudatus (Blue-Winged Olive) Mayfly Dun View 6 PicturesThis one emerged from a nymph of this kind in my studio but got a bit waterlogged before I could pull it out to photograph.
Collected September 12, 2020 from the Yakima River in Washington
Added to Troutnut.com by Troutnut on September 19, 2020
Female Baetis tricaudatus (Blue-Winged Olive) Mayfly NymphFemale Baetis tricaudatus (Blue-Winged Olive) Mayfly Nymph View 13 PicturesThese nymphs were highly abundant in my early April kick net samples from the Yakima Canyon, and one of them emerged into a dun, which I photographed immediately. Similar-looking nymphs but with distinctly brighter color patterns were also abundant. I just photographed one. After extensive views under the microscope, it's clear the bright ones are males and the dull ones are females of the same species.

The most likely guess at the species is Baetis tricaudatus, which may be a complex of related species that haven't all been sorted out yet. It isn't a perfect fit to every key characteristic (and I never seem to find a Baetis that matches the expected pronotum (Pronotum: The top of the insect prothorax.) color patterns, but that seems to be the closest.

The microscope images here were taken with different specimens from the main photos (so I could dissect them while preserving that one intact), but clearly the same species.
Collected April 9, 2021 from the Yakima River in Washington
Added to Troutnut.com by Troutnut on April 12, 2021
Male Baetis tricaudatus (Blue-Winged Olive) Mayfly NymphMale Baetis tricaudatus (Blue-Winged Olive) Mayfly Nymph View 14 PicturesThis specimen and many like it were found with other specimens I found to be duller-colored females of the same species. I wasn't aware of such a difference between male and female nymphs in Baetids, but all the morphological characteristics I checked in the key were the same, and the color patterns are, too -- just not the brightness.
Collected April 9, 2021 from the Yakima River in Washington
Added to Troutnut.com by Troutnut on April 12, 2021
Female Baetis tricaudatus (Blue-Winged Olive) Mayfly SpinnerFemale Baetis tricaudatus (Blue-Winged Olive) Mayfly Spinner View 5 PicturesThis female spinner was deceased when photographed, so the posture is unnatural, but it was a substantial hatch and clearly worth imitating (with wet flies to imitate the sunken ovipositing females) so I went ahead with the photos.

It was collected in association with a male spinner.
Collected September 4, 2020 from Silver Creek in Idaho
Added to Troutnut.com by Troutnut on September 18, 2020
Baetis (Blue-Winged Olives) Mayfly AdultBaetis (Blue-Winged Olives) Mayfly Adult View 1 Pictures
Collected March 1, 2005 from the Jocko River in Montana
Added to Troutnut.com by Bnewell on June 28, 2011
Specimen Page:1234
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