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Insect Order Ephemeroptera (Mayflies)



Pictures Below

This is page 55 of specimens of Ephemeroptera. Visit the main Ephemeroptera page for:

  • The behavior and habitat of Ephemeroptera.
  • 67 underwater pictures of Ephemeroptera.

Pictures of 828 Mayfly Specimens:

Specimen Page:1...545556...84
Male Baetis bicaudatus (BWO) Mayfly NymphMale Baetis bicaudatus (BWO) Mayfly Nymph View 7 PicturesThis specimen was collected along with a female which was quite a bit larger, different in color, but otherwise seemed the same morphologically.
Collected April 12, 2021 from Holder Creek in Washington
Added to Troutnut.com by Troutnut on April 13, 2021
Female Baetis bicaudatus (BWO) Mayfly NymphFemale Baetis bicaudatus (BWO) Mayfly Nymph View 12 PicturesI collected this one along with a male that was quite a bit smaller but equally ready to emerge in mid April.

I spent (Spent: The wing position of many aquatic insects when they fall on the water after mating. The wings of both sides lay flat on the water. The word may be used to describe insects with their wings in that position, as well as the position itself.) quite a while on the identifications, because they really don't look very much like the Baetis bicaudatus nymph I caught last year in Idaho. However, the presence of hind wing pads (
The wing pads on this final instar Baetidae mayfly nymph are extremely dark.
The wing pads on this final instar Baetidae mayfly nymph are extremely dark.
Wing pad: A protrusion from the thorax of an insect nymph which holds the developing wings. Black wing pads usually indicate that the nymph is nearly ready to emerge into an adult.
)
rules out Acentrella turbida, the lack of a fringe of long setae (Seta: Little hairs on insects.) on the tibiae (
The tibia of this Isonychia bicolor mayfly spinner is highlighted in red.
The tibia of this Isonychia bicolor mayfly spinner is highlighted in red.
Tibia: A middle segments in the leg of an insect, located between the femur and the tarsus.
)
rules out Acentrella insignificans, range rules out Heterocloeon and Iswaeon, and the thumb-like projection on the labial palp (
The palp on the maxilla of an Ephemerella nymph (detached and photographed under a microscope) is highlighted in red here.
The palp on the maxilla of an Ephemerella nymph (detached and photographed under a microscope) is highlighted in red here.
Palp: A long, thin, often segmented appendage which can protrude from certain insect mouth parts such as the maxillae. Also known as the < />palpus.
)
points to Baetis. Thus, Baetis bicaudatus is a fairly confident ID, and it's not too surprising that it looked different from my previous specimen because bicaudatus is thought to be a species complex with multiple types that haven't been fully sorted out yet.

The microscope pictures for this specimen aren't from the same exact nymph, but a mixture of a few others of the same kind that I didn't mind dissecting.
Collected April 12, 2021 from Holder Creek in Washington
Added to Troutnut.com by Troutnut on April 13, 2021
Female Baetidae (Blue-Winged Olives) Mayfly DunFemale Baetidae (Blue-Winged Olives) Mayfly Dun View 7 PicturesThis specimen was collected on the same trip as a similar dun.
Collected May 28, 2005 from the Namekagon River in Wisconsin
Added to Troutnut.com by Troutnut on May 24, 2006
Drunella flavilinea (Flav) Mayfly NymphDrunella flavilinea (Flav) Mayfly Nymph View 6 PicturesAlthough the identification is not certain because the nymph is not yet mature, the configuration of tubercles (
A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled.  They are especially large in this species.
A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled. They are especially large in this species.
Tubercle: Various peculiar little bumps or projections on an insect. Their character is important for the identification of many kinds of insects, such as the nymphs of Ephemerellidae mayflies.
)
on this one--particularly the forefemora--seems to best match Drunella flavilinea.
Collected July 2, 2019 from the Gallatin River in Montana
Added to Troutnut.com by Troutnut on July 18, 2019
Male Paraleptophlebia sculleni Mayfly SpinnerMale Paraleptophlebia sculleni  Mayfly Spinner View 10 PicturesFor a species not yet reported in my state, I've been surprised to find these in two different locations lately. I was tempted to think they're the more common Paraleptophlebia debilis, but the characteristic big dorsal (Dorsal: Top.) bump on the claspers (
The claspers of this male Hexagenia atrocaudata mayfly spinner are highlighted in green.
The claspers of this male Hexagenia atrocaudata mayfly spinner are highlighted in green.
Clasper: The claspers, also known as forceps, are a pair of appendages beneath the tip of the abdomen of male mayfly adults, which are used to grab onto the female while mating.
)
just isn't present.
Collected August 4, 2019 from the Middle Fork Snoqualmie River in Washington
Added to Troutnut.com by Troutnut on August 5, 2019
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 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
Specimen Page:1...545556...84
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