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Ephemeroptera: Baetidae of Gunnison County, Colorado

Diphetor hageni
Hagen's Small Minnow Mayfly, Iron Blue Quill, Light Blue Dun, Dark blue winged Olive #20

(Eaton) 1885

Updated 20 July 2022
TSN 568598


D. hageni larvae have no gills on the first abdominal segment, their abdominal gills start on the second segment. Larvae also have a tuft of setae on the right mandible between the incisors and prostheca. They are three-tailed, small dark larvae present in the early summer in the East River near Gothic among other places. After preservation in ethanol, the distinctive dark color is lost. The BugLab in Utah notes the larvae have a keel on their head between their antennae.


Split from Baetis by Waltz and McCafferty (1987). Many scientific and flyfishing sources refer to this species as Baetis hageni. In Wisconsin, D. hageni was found to be parthenogenic. Populations in Illinios and Indiana have males. I don't know about the sex ratios of our local populations yet!

Good Links

On this website:
Baetidae Introduction
Key to Baetidae Nymphs

Other Websites:
    Synonyms from the Mayflies of North America accessed 4 June 2009.
    Diphetor hageni (Eaton), 1885 [CAN:FN,NE,NW;USA:FN,NE,NW,SE,SW]
        * Baetis devinctus Traver, 1935 (syn.)
        * Baetis hageni Eaton, 1885 (renam.)
        * Baetis herodes Burks, 1953 (syn.)
        * Baetis parvus Dodds, 1923 (syn.)
        * Baetis unicolor (Hagen), 1861 (hom.comb.)
        * Cloe unicolor Hagen, 1861 (hom.: C. unicolor Curtis, 1834)
        * Diphetor devinctus (Traver), 1935 (syn.)


    Ball,SL; Hebert,PDN; Burian,SK; Webb,JM 2005 Biological identification of mayflies (Ephemeroptera) using DNA barcodes. Journal of the North American Benthological Society 24 3, 508-524.

    Bergman, EA and WL Hilsenhoff 1978 Parthenogenisis in the mayfly genus Baetis (Ephemeroptera: Baetidae). Annals of the Entomological Society of America 71:167-168.
         Discussed as Baetis hageni. They found that D. hageni was parthenogenic in the lab. They mention that northern populations of D. hageni frequently lack males. They observed virgin Baetis species which readily laid eggs when held in the water were parthenogenic, while the animals that had to have their eggs dissected out did not hatch. Other labs mentioned in this paper found parthenogenic species that would not oviposit in captivity, so this does not always hold true. They also noted the non-parthenogenic animals had eggs with more adhesive which indicates a different type of oviposition behavior.

    DeWalt,RE; Stewart,KW; Moulton,SR; Kennedy,JH 1994 Summer emergence of mayflies, stoneflies, and caddisflies from a Colorado mountain stream. Southwestern Naturalist 39 3, 249-256.

    Dodds,GS 1923 Mayflies from Colorado: descriptions of certain species and notes on others. Transactions of American Entomological Society 69, 93-116.
         Discussed as Baetis parvus.

    Eaton AE. 1883-1888. A revisional monograph of recent Ephemeridae or mayflies. Transactions of the Linnean Society of London, Second Series, Zoology 3:1-352, 65 pl.
         On page 169, Eaton decided this was a Baetis species and that it had the wrong species name. This used to be called Cloe unicolor until Eaton noticed unicolor was taken by another species. So he named it Baetis hageni to respect the taxonomist (H. Hagen) who originally named this species. Of course this wasn't the last word, there were many name changes and synonymies to come, see Meyer and McCafferty and Waltz and McCafferty.

    Gilpin,BR and Brusven,MA 1970 Food habits and ecology of mayflies of the St. Maries River in Idaho. Melanderia 4:19-40. PDF
         Discussed as Baetis parvus.

    McCafferty,WP; Durfee,RS; Kondratieff,BC 1993 Colorado mayflies (Ephemeroptera): an annotated inventory. Southwestern Naturalist 38 3, 252-274. PDF
         Quote from page 258: "This is a distinctive, transcontinental species known from British Columbia to Quebec and south to North Carolina, Indiana, Missouri and Colorado. "

    McCafferty,WP Meyer,MD; Randolph,RP and Webb,JM 2008 Evaluation of mayfly species originally described as Baetis Leach (Ephemeroptera: Baetidae) from California. Proceedings of the Entomological Society of Washington, 110(3) 577-591.

    McNamara,AE; Hill,WR 1999 Effects of UV dose and irradience: comparison among grazers. Journal of the North American Benthological Society 18 3, 370-380.Abstract

    Mebane,CA; Schmidt,TS; Miller,JL and Balistrieri,LS 2020 Bioaccumulation and toxicity of cadmium, copper, nickel, and zinc and their mixtures to aquatic insect communities. Environmental toxicology and chemistry, 39(4) 812-833. PDF

    Meyer,MD; McCafferty,WP 2001 Hagen's small minnow mayfly (Ephemeroptera:Baetidae) in North America. Entomological News 112 4, 255-263.
         Synonymizes the species Diphetor devinctus from California with D. hageni. Has a detailed discussion of the name changes D. hageni has suffered. To summarize, this species was first named Cloe unicolor, which was changed because it was in the wrong genus and someone else had already used the name unicolor for another species. However, the name proposed, Baetis hageni was ignored by most taxonomic workers in the early and mid 1900s who called it Baetis unicolor instead. Then in 1962 Edmunds explained why B. hageni was better and everyone followed that until Waltz and McCafferty created a new genus Diphetor. Other species that have been synonymized or merged with D. hageni in the past include Baetis herodes and Baetis parvus. There are more details I am skipping including Palearctic records of other species that really aren't in the genus Diphetor, but once were erroneously called as such. Whew! That's where we're at today with the name of this species. They also have illustrations of the variability in male genitalia and adult hindwings. This variation explains some of the confusion.

    Morihara,DK; McCafferty,WP 1979a The Baetis larvae of North America (Ephemeroptera:Baetidae). Transactions of American Entomological Society 105, 139-221.
         Discussed as Baetis hageni. They synonymized Baetis parvus with B. hageni and noticed how similar B. hageni was to what was called at the time Baetis devinctus.

    Peckarsky,BL; Encalada,AC and McIntosh,AR 2011 Why do vulnerable mayflies thrive in trout streams?. American Entomologist, 57(3), pp.152-164. PDF

    Poff,NL; Olden,JD; Viera,NKM; Finn,DS; Simmons,MP; Kondratieff,BC 2006 Functional trait niches of American lotic insects: traits-based ecological applications in light of phylogenetic relationships. Journal of the North American Benthological Society 25 4, 730-755.
         Here are the traits for this species from the Appendix:
    Life History Voltinism Bi or multivoltine - more than 1 generation/yr
    Development Fast Seasonal
    Synchronization of emergence Poorly synchronized
    Adult life span Less than 1 week
    Adult ability to exit Absent
    Ability to survive dessication Absent
    Mobility Female dispersal Less than 1km flight before laying eggs
    Adult flying strength Weak - cannot fly into light breeze
    Occurance in drift Rare (catastrophic only)
    Maximum crawling rate Low - less than 100cm/hour
    Swimming ability Strong
    Morphology Attachment None (free ranging)
    Armoring None (soft -bodied forms)
    Shape Streamlined (fusiform)
    Respiration Gills
    Size at maturity Small (less than 9mm)
    Ecology Rheophily Depositional and erosional
    Thermal preference Cool/Warm eurythermal
    Habit Swim
    Trophic habit Collector-gatherer

    Stauffer-Olsen,NJ; O'Grady,PM and Resh,VH 2019 Cytochrome oxidase I sequences from northern and southern California suggest cryptic Baetis (Ephemeroptera: Baetidae) species. Western North American Naturalist, 79(2) 204-218. PDF

    Waltz RD; McCafferty WP. 1987a New genera of Baetidae for some Nearctic species previously in Baetis Leach (Ephemeroptera). Annals of the Entomological Society of America 80:667-670.
         Created the genus Diphetor and called Diphetor hageni the type species.

    Waltz,RD; McCafferty,WP 1997 New generic synonymies in Baetidae (Ephemeroptera). Entomological News 108 2, 134-140.

    Ward,JV; Stanford,JA 1990 Ephemeroptera of the Gunnison River, Colorado, USA. In: Mayflies and Stoneflies. Ed: Campbell,IC Kluwer Academic Publishers, 215-220.
         Discussed as Baetis hageni.

    Brown, Wendy S. 2004 Mayflies (Ephemeroptera) of Gunnison County, Colorado, USA