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Mayfly Family Baetidae (Blue-Winged Olives)



Pictures Below ↓

This is page 6 of specimens of Baetidae. Visit the main Baetidae page for:

  • The behavior and habitat of Baetidae.
  • 10 underwater pictures of Baetidae.

Pictures of 103 Mayfly Specimens in the Family Baetidae:

Specimen Page:1...567...11
Baetidae (Blue-Winged Olives) Mayfly NymphBaetidae (Blue-Winged Olives) Mayfly Nymph View 2 PicturesHere's a rather different tiny Baetid nymph. The tails are all unbanded, and the tergites (
One tergite of this Isonychia bicolor mayfly spinner is highlighted in red.
One tergite of this Isonychia bicolor mayfly spinner is highlighted in red.
Tergite: The top (dorsal) part of a single segment on an insect's abdomen when it consists of a single chitinous plate (sclerite), or an individual sclerite if the segment has more than one.) all have a dark-colored anterior (Anterior: Toward the front of an organism's body. The phrase "anterior to" means "in front of.") 2/3 and light-colored posterior (Posterior: Toward the back of an organism's body. The phrase "posterior to" means "in back of.") 1/3. The gill veinlets (Veinlet: Short insect wing veins connecting the major longitudinal veins to the wing margin.) are indistinct. It's probably a very early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.) of some Baetis species.
Collected January 31, 2004 from unknown in Wisconsin
Added to Troutnut.com by Troutnut on January 25, 2006
Male Baetis flavistriga (BWO) Mayfly NymphMale Baetis flavistriga (BWO) Mayfly Nymph View 8 PicturesThis nymph keys to Baetis assuming the villipore is present (hard to see in my photos or scope), and within that genus it tentatively keys to the flavistriga species complex, of which Baetis flavistriga itself is by far the most common in Washington state, so that's the most likely ID.
Collected July 6, 2020 from Mystery Creek #249 in Washington
Added to Troutnut.com by Troutnut on July 12, 2020
Baetis flavistriga (BWO) Mayfly NymphBaetis flavistriga (BWO) Mayfly Nymph View 1 Pictures
Collected June 19, 2011 from the Kwethluk River in Alaska
Added to Troutnut.com by Bnewell on June 26, 2011
Procloeon pennulatum (Tiny Sulphur Dun) Mayfly NymphProcloeon pennulatum (Tiny Sulphur Dun) Mayfly Nymph View 1 PicturesThis fragile nymph is easily damaged during sampling making identification more difficult.
Collected June 19, 2009 from Murphy Lake in Montana
Added to Troutnut.com by Bnewell on June 26, 2011
Baetidae (Blue-Winged Olives) Mayfly NymphBaetidae (Blue-Winged Olives) Mayfly Nymph View 2 Pictures
Collected January 13, 2004 from the Namekagon River in Wisconsin
Added to Troutnut.com by Troutnut on January 25, 2006
Female Acentrella turbida (Tiny Blue-Winged Olive) Mayfly SpinnerFemale Acentrella turbida (Tiny Blue-Winged Olive) Mayfly Spinner View 1 PicturesHere is the female spinner of the tiny Acentrella turbida. You can see the coloration is quite different from the male.
Collected July 27, 2011 from the Touchet River in Washington
Added to Troutnut.com by Bnewell on July 29, 2011
Baetidae (Blue-Winged Olives) Mayfly NymphBaetidae (Blue-Winged Olives) Mayfly Nymph View 3 PicturesClose examination under a microscope revealed that this Baetid nymph has segment 5 pale, segments 8, 9, and 10 pale but less so, a middle tail almost as long as the outer tails, conspicuous gill veinlets (Veinlet: Short insect wing veins connecting the major longitudinal veins to the wing margin.), no bands on its tails, and pointed, slender 7th gills.
Collected February 7, 2004 from unknown in Wisconsin
Added to Troutnut.com by Troutnut on January 25, 2006
Male Callibaetis (Speckled Spinners) Mayfly SpinnerMale Callibaetis (Speckled Spinners) Mayfly Spinner View 4 Pictures
Collected August 11, 2018 from the Henry's Fork of the Snake River in Idaho
Added to Troutnut.com by Troutnut on June 12, 2019
Baetis bicaudatus (BWO) Mayfly NymphBaetis bicaudatus (BWO) Mayfly Nymph View 5 PicturesHere I'm just copying and pasting, without cleaning up, my notes from spending a long time with this one under the microscope (and keying with Merritt & Cummins 5th Ed) only to end up confirming the most likely guess.

7. Baetis bicaudatus nymph
1. Hind wingpad present but small and hidden beneath forewing pad
2. Segment 2 of 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.) with well-developed medially projecting corner —> Baetis (couple 44)…. BUT no sign of scale-like setae (Seta: Little hairs on insects.) on abdominal terga (Tergum: the dorsal part of an abdominal segment or segments (terga). Also used to describe the entire abdominal dorsum or the thoracic dorsal segments of Odonata.). Conflicts at this couplet.
3. Gills on segments I-VII
4. Tarsal claws (Tarsal claw: The claws at the tip of the tarsus, on an insect's "foot.") with denticles (
View Full Size
The denticles on the tarsal claw of this Ephemerella nymph are highlighted in red.
The denticles on the tarsal claw of this Ephemerella nymph are highlighted in red.
Denticle: Small tooth-like projects, often appearing like serrations on the tarsal claws of certain mayfly nymphs.), seemingly 2 rows but very hard to tell… and the key options with 2 rows don’t make sense
5. Assuming no villipore, we land confidently at couplet 48
6. Leads to Fallceon, except antennal scape doesn’t have robust setae (Seta: Little hairs on insects.)
7. Treated as Baetis, leads to brunneicolor, but McDunnough et al 1932 (Can Ent 64) suggests middle tail should be 5/6 as long as outer ones
8. Keys VERY confidently to couplet 36 in M&C (villipore)
9. If assuming villipore present:
1. 37 —> Scape of anntenae has no distal (Distal: Far from the point of attachment or origin; near the tip.) lobe —> rules out Labiobaetis (100 % certain)
2. 38 —> Terminal filament much shorter than cerci (Cercus: The left and right "tails" of an insect are known as the cerci or caudal cerci. The middle tail of a three-tailed insect is not.) —> not Barbaetis benfieldi (100 % certain)
3. 39 —> Terminal filament reduced (100 % certain)
4. 40 —> Tarsal claw (Tarsal claw: The claws at the tip of the tarsus, on an insect's "foot.") dentical count couplet. If two rows of denticles (
View Full Size
The denticles on the tarsal claw of this Ephemerella nymph are highlighted in red.
The denticles on the tarsal claw of this Ephemerella nymph are highlighted in red.
Denticle: Small tooth-like projects, often appearing like serrations on the tarsal claws of certain mayfly nymphs.): Either Iswaeon or Heterocloeon. Can’t be Iswaeon because cerci (Cercus: The left and right "tails" of an insect are known as the cerci or caudal cerci. The middle tail of a three-tailed insect is not.) lack dark median band. Can’t be heterocloeon because it’s not in the Platte drainage or in Texas. Thus, it must be one row of denticles (
View Full Size
The denticles on the tarsal claw of this Ephemerella nymph are highlighted in red.
The denticles on the tarsal claw of this Ephemerella nymph are highlighted in red.
Denticle: Small tooth-like projects, often appearing like serrations on the tarsal claws of certain mayfly nymphs.). Moving on to 42.
5. 42 —> 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.) present (100 % certain)
6. 44 —> Segment 2 of labial palpi with well-developed medially projecting corner (80 % certain), scale-like setae (Seta: Little hairs on insects.) not evident on terga (Tergum: the dorsal part of an abdominal segment or segments (terga). Also used to describe the entire abdominal dorsum or the thoracic dorsal segments of Odonata.) but maybe limitation of my scope —> Baetis (alternative would be Acentrella, but pronotum (Pronotum: The top of the insect prothorax.) shape is all wrong for those, although not an official characteristic)
7. CONFIDENT in Baetis bicaudatus after distinctive leg markings (J-shaped light mark on first femur (
The femur of this Isonychia bicolor mayfly spinner is highlighted in red.
The femur of this Isonychia bicolor mayfly spinner is highlighted in red.
Femur: The main segment of an insect's leg close to the body, in between the tibia and the trochanter.), L-shaped on second and third) matches original species description to a tee.
Collected August 4, 2020 from Green Lake Outlet in Idaho
Added to Troutnut.com by Troutnut on August 20, 2020
Female Baetidae (Blue-Winged Olives) Mayfly SpinnerFemale Baetidae (Blue-Winged Olives) Mayfly Spinner View 8 Pictures
Collected May 26, 2005 from the Namekagon River in Wisconsin
Added to Troutnut.com by Troutnut on May 16, 2006
Specimen Page:1...567...11
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