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Iron Blue Quills

Like most common names, "Iron Blue Quill" can refer to more than one taxon. They're previewed below, along with 6 specimens. For more detail click through to the scientific names.

Mayfly Species Diphetor hageni

These are often called Iron Blue Quills.
This is one of the most important species of the Baetidae family. Previously known as Baetis parvus in the West and its synonym (Synonym: A former name of a taxon, usually a species. Entomologists frequently discover that two insects originally described as different species are one in the same, and they drop one of the names. The dropped name is said to be a synonym of the remaining name. These changes take a while to trickle into the common knowledge of anglers; for example, Baetis vagans is now a synonym of Baetis tricaudatus.) Baetis devinctus in the East, it is distributed across the country but most of its fame comes from excellent hatches in the West. Prior to all the species being combined with Baetis tricaudatus, most angling literature considered it the most populous and widespread western species of the Baetidae family.

Dorsal (Dorsal: Top.) abdominal markings on the nymphs used to differentiate the species in these older works have since proved unreliable. The easiest way to tell them apart from B. tricaudatus is their lack of gills on the first abdominal segment. Telling adults apart is equally tough. Duns of D. hageni are typically a little smaller, but their bodies can also be olive, brownish olive and even two toned with thoraxes a shade of brown or tan with paler olivacious abdomens.

Diphetor hageni has two former names used in angling literature, Baetis parvus in the West and Baetis divinctus in the East.
Diphetor hageni (Little Blue-Winged Olive) Mayfly NymphDiphetor hageni (Little Blue-Winged Olive) Mayfly Nymph View 6 Pictures
Collected July 25, 2019 from in
Added to Troutnut.com by on July 26, 2019

Mayfly Species Baetis magnus

These are often called Iron Blue Quills.
This large western baetid is in the Rhodani group of closely related species that could probaly also be called the baetis tricaudatus species complex. Besides its large overall size, large hind wings (for a baetid) with rounded margins and dark lateral (Lateral: To the side.) bands of pigment on the abdomen are are also characteristic.

Mayfly Species Labiobaetis propinquus

These are sometimes called Iron Blue Quills.
This species was previously known as Baetis propinquus, a name from older nomenclatures and angling literature familiar to many western anglers. Prior to its current listing, it did a brief stint in the genus Pseudocloeon. The irony is that though this species has hind wings, it was the last species remaining in Pseudocloeon (before the genus recent Nearctic taxonomic demise) which was best known for its species lacking hind wings as an identifying character.

Though it has a national distribution its most important hatches occur in the West, usually hatching between the larger broods of Baetis tricaudatus. Western anglers experiencing a hatch can easily confuse them with the larger Baetis bicaudatus as both nymphs appear similar with only two tails. Besides size, the adults can be separated from bicaudatus (with the help of a little magnification) because L. propinquus lacks acute costal projections (
The costal projection of a Baetidae dun.
The costal projection of a Baetidae dun.
Costal projection: A bump or point sticking up from the front margin of an insect's wing, usually the rear wing of certain mayflies. It is sometimes called a costal process.
)
on its tiny hind wings. Conversely, the presence of hind wings and lack of conical mesonotal projections (Conical mesonotal projection: small cone shaped spike sticking up from the top and front part of the middle thorax segment.) makes them easy to tell from the more common and equally tiny Acentrella turbida.

Mayfly Species Baetis tricaudatus

These are sometimes called Iron Blue Quills.
Baetis tricaudatus is undeniably the most widespread and abundant baetid on the continent and arguably the most important mayfly species to trout and anglers alike. Eastern anglers used to know these important mayflies by the storied name of Baetis vagans. Conversely, the usually much larger and late Fall hatching brood of Baetis tricaudatus was considered an important Western species with its own tradition. But, entomologists recently determined that they are both in fact the same species. The nomenclature conventions guiding entomologists do not account for a name's regional fame among fishermen, and new or obscure species names may replace their old favorites. Sometimes taxa with disparate traditions are combined. Baetis vagans is one such casualty. Fortunately, trout think like Shakespeare: A rose by any other name would smell as sweet. The rose that was vagans has lost none of its charm. This species is multibrooded (Multibrooded: Producing more than one generation in a single year. Baetis mayflies are a classic example. Insects which produce a single generation with two distinct peaks (like the June and September hatches of Isonychia bicolor mayflies) are not multibrooded, because the fall insects are offspring from the previous fall instead of the current year's spring.) with the hatches of Spring being larger flies. As the weather warms the following broods are composed of progressively smaller flies. In the East, they range in size from 16 to 20. In the West, they may run a size larger.
Baetis tricaudatus (Blue-Winged Olive) Mayfly NymphBaetis tricaudatus (Blue-Winged Olive) Mayfly Nymph View 20 PicturesA nymph of the same species as this one emerged into a dun in my studio so I got photos of both stages.

NOTE: I missed an important key characteristic the first time I tried to identify this one (robust setae (Seta: Little hairs on insects.) on the abdominal sternites (
One sternite of this Isonychia bicolor mayfly spinner is highlighted in red.
One sternite of this Isonychia bicolor mayfly spinner is highlighted in red.
Sternite: The bottom (ventral) part of a single segment on an insect's abdomen.
)
, which were harder to see than I expected but are clearly present), so I went on a bit of a wild goose chase and landed at a dead end. After spotting that characteristic, this one keys more straightforwardly to either Baetis tricaudatus or the Baetis piscatoris complex. It doesn't seem to be a perfect fit for either one in the key, but I'm going with tricaudatus based on range and abundance. It's not certain.

However, I'm leaving the flawed analysis below with this disclaimer, because some aspects of how I approached that dead end might be informative in the future.

----Incorrect analysis below----

After spending a lot of time with this one under my shiny new microscope, I'm still not quite sure what it is. I botched my attempt to expose the mouth parts that might make the ID more definitive. Based on the key in Webb et al 2018's "Baetis Larvae of North America," here's my reasoning at each key couplet.

Couplet 1. The pronotum (Pronotum: The top of the insect prothorax.) lacks dark, submedian U-shaped markings. Also, if I were to follow through to couplet 2, there seem to be characteristics that rule out each of the options: the intercalaris complex is ruled out by the abdominal markings, and the caudal (Caudal: Toward the posterior tip of the body.) filaments have neither a dark median band (ruling out the flavistriga complex) nor uniform pale coloration (ruling out Baetis notos). This sends me with decent confidence to couplet 4.

Couplet 4. I cannot find robust setae (Seta: Little hairs on insects.) in my microscope on the scapes, pedicels, paraprocts, or sterna. I also do not see a pair of dark, bilobed markings on the pronotum (Pronotum: The top of the insect prothorax.). Unless I overlooked these characteristics, proceed to couplet 9.

Couplet 9. Abdominal tergum (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.) 5 is a bit paler than adjacent 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 "distinctly paler"? The figure for Baetis alius in the paper, as well as a very nice picture posted by Millcreek in the forum here, shows that Baetis alius would have darker 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.
)
surrounding #5. So proceed to couplet 11.

Couplet 11. The length of the gills is obviously less than 2X their width. This leads to the Baetis vernus complex, which could include that species or Baetis brunneicolor. This key doesn't say how to tell those species apart.

Switching over to Burien et al 2018 as the source, the characteristics used to distinguish vernus from brunneicolor seem to rule out either one. Brunneicolor should have more uniformly brown abdominal 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.
)
, whereas vernus should have a lack of visible tracheation in most of the gills.

The fore 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.
)
length is about 3.8x its width.

Also worth noting: In the genus ID, I thought I could see the villipore in my microscope, but I'm not sure. If I back out of Baetis altogether and assume there's no villipore, I end up at Fallceon, but this specimen doesn't seem to have the frontal keel on the head that's supposed to be present on Fallceon quilleri. So that seems like a dead end as well.
Collected September 12, 2020 from in
Added to Troutnut.com by on September 19, 2020
Male Baetis tricaudatus (Blue-Winged Olive) Mayfly DunMale Baetis tricaudatus (Blue-Winged Olive) Mayfly Dun View 8 PicturesThis male was associated with a female of the same species.
Collected April 3, 2007 from in
Added to Troutnut.com by on April 3, 2007
Male Baetis tricaudatus (Blue-Winged Olive) Mayfly SpinnerMale Baetis tricaudatus (Blue-Winged Olive) Mayfly Spinner View 1 Pictures
Collected April 15, 2010 from in
Added to Troutnut.com by on June 27, 2011
Male Baetis tricaudatus (Blue-Winged Olive) Mayfly AdultMale Baetis tricaudatus (Blue-Winged Olive) Mayfly Adult View 2 Pictures
Collected May 16, 2012 from in
Added to Troutnut.com by on May 18, 2012

Mayfly Species Neoleptophlebia mollis

These are very rarely called Iron Blue Quills.
This species often emerges together with Paraleptophlebia strigula and Paraleptophlebia guttata, and the combined effect can be a good fishable hatch. The latter two are much less famous than mollis, but Knopp and Cormier say they are more reliable.
Male Neoleptophlebia mollis (Jenny Spinner) Mayfly DunMale Neoleptophlebia mollis (Jenny Spinner) Mayfly Dun View 6 Pictures
Collected June 8, 2005 from in
Added to Troutnut.com by on May 26, 2006
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