» Order Ephemeroptera (Mayflies)
8 families (Acanthametropodidae, Ametropodidae, Arthropleidae, Behningiidae, Euthyplociidae, Oligoneuriidae, Palingeniidae, Pseudironidae)
aren't included.
Common Name
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:
Female 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.
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 (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.
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. Drunella 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.
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. Male 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 (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. Female 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.