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Ephemeroptera: Baetidae of Gunnison County, Colorado

Baetis tricaudatus
Iron Blue Quill, Light Rusty Spinner, Blue winged Olive (5) (BWO), Dark blue winged Olive #18-20, Little Blue Dun, Little Blue Quill

Dodds 1923

Updated 12 May 2021


Larvae have dark bilobed marks in the center of the pronotum. They have three unbanded tails, the center filament is relatively long and thick in many animals. Gill margins are serrate with fine setae.

Locations Collected

East River, Gunnison River, Coal Creek. Baetis tricadatus is one of the most widespread Baetis species in North America.


Known to eastern flyfishermen as Baetis vagans, but now combined with Baetis tricaudatus. Recently Baetis mofatti was synonymized (merged taxonomically) with B. tricaudatus as well. This is one of the rhodani species group of Baetis.

Good Links

On this website:
Introduction to Baetis
Key to Baetis Nymphs

Other Websites:
Hatch Chart for the Gunnison Gorge & Black Canyon from Cimarron Creek Guides in Montrose http://cimarroncreek.com/flyfishing/hatchchart.cfm

PAN Pesticides database: http://www.pesticideinfo.org/PCW/List_AquireAll.jsp?Species=5335


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. PDF

Bergey,EA and Ward,JV 1989 Upstream-downstream movements of aquatic invertebrates in a Rocky Mountain stream, Hydrobiologia, Volume 185( 1) 71-82. Abstract
     Baetis tricaudatus showed a size difference in drift behavior. Smaller animals tended to stay on the bottom, drifting less than larger animals. At the same time, nymphs moving during the day were significantly smaller than those moving at night.

Brinkman,SF and Johnston,WD 2012 Acute toxicity of zinc to several aquatic species native to the Rocky Mountains. Archives of Environmental Contamination and Toxicology, 62(2), 272-281.

Carlisle,Daren M; Clements,William H 2003 Growth and secondary production of aquatic insects along a gradient of Zn contamination in Rocky Mountain streams. Journal North American Benthological Society 22(4), 582-597. Abstract and entire paper

Clements,WH 1999 Metal tolerance and predator-prey interactions in benthic macroinvertebrate stream communities. Ecological Applications 9, 1073-1084.

Clements,WH; Carlisle,DN; Lazorchak,JM; Johnson,PC 2000 Heavy metals structure benthic communities in Colorado mountain streams. Ecological Applications 10(2)626-638. Abstract

Corkum LD and Clifford HF 1981 Function of caudal filaments and correlated structures in mayfly nymphs, with special reference to Baetis (Ephemeroptera). Quaestiones Entomologicae 17:129-146. PDF

Culp,JM and Scrimgeour,GJ 1993 Size-dependent diel foraging periodicity of a mayfly grazer in streams with and without fish. Oikos 68(2)242-250. PDF

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. PDF

Dobrin,M and Giberson, DJ 2004 Life history and production of mayflies, stoneflies, and caddisflies (Ephemeroptera, Plecoptera, and Trichoptera) in a spring-fed stream in Prince Edward Island, Canada: evidence for population asynchrony in spring habitats? Can. J. Zool./Rev. Can. Zool. 81(6): 1083-1095

Dodds,GS 1923 Mayflies from Colorado: descriptions of certain species and notes on others. Transactions of American Entomological Society 69, 93-116. PDF
     Dodds described Baetis tricaudatus from South Boulder Creek in the early 1900s. He also describes Baetis intermedius which has been synonymized (combined taxonomically) with B. tricaudatus. Quote from page 112: "Lives in moderately swift streams, but not in as swift parts as either of the preceding nymphs (B. bicaudatus and intermedius). In south Boulder Creek and its tributaries, 5,500 to 11,150 feet."

Dosdall, LM; Goodwin, LR; Casey, RJ; Noton, L 1997 The effect of ambient concentrations of chlorate on survival of freshwater aquatic invertebrates. Water Quality Research Journal of Canada. 32(4) 839-854.
      Also mentioned in the PAN pesticides database link above and on the Ambient Water Quality Guidelines for Chlorate website from Government of British Columbia, Ministry of the Environment.

Durfee,R and Kondratieff,BC 1993 Description of adults of Baetis magnus (Ephemeroptera:Baetidae). Entomological News 104 (5) 227-232.
    They discuss the details of telling this species apart from Baetis magnus.

Durfee,RS and Kondratieff,BC 1999 Notes on North American Baetis (Ephemeroptera: Baetidae):Baetis moffatti new synonym of B. tricaudatus and range extension for B. bundyae. Entomological News 110 3, 177-180.

Edmunds Jr, GF 1995 Habitat differences between northern and southern populations of mayflies of the western United States. Pages 171-176 in Corkum LD; Ciborowski JJH. Current Directions in Research on Ephemeroptera. Canadian Scholars' Press, Inc. Toronto.

Fuller,RL; Roelofs,JL and Fry,TJ. 1986 The importance of algae to stream invertebrates. Journal of the North American Benthological Society 5(4)290-296. PDF

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

Glozier,NE; Culp,JM; Scrimgeour,GJ; Halliwell,DB 2000 Comparison of gut fluorescence and gut dry mass techniques for determining feeding periodicity in lotic mayflies. Journal of the North American Benthological Society 19(1):169-175. PDF

Hamilton,H and Clifford, F 1983 The seasonal food habits of mayfly (Ephemeroptera) nymphs from three Alberta, Canada, streams, with special reference to absolute volume and size of particles ingested. Arch. Hydrobiol., Suppl, 65(2/3), 197-234. PDF

Harper,PP and Harper,H 1997. Mayflies (Ephemeroptera) of the Yukon. Pp. 152-167 In: H.V. Danks and J.A. Downes, eds. Insects of the Yukon. Biological Survey of Canada (Terrestrial Arthropods). Ottawa, Ontario, Canada. http://www.biology.ualberta.ca/bsc/pdf/harper.pdf

Irving,EC; Baird,DJ; Culp,JM 2003 Ecotoxicological responses of the mayfly Baetis tricaudatus to dietary and waterborne cadmium: implications for toxicity testing. Environmental Toxicology and Chemistry 22, 1058-1064.
     Abstract: " Trace metals readily accumulated by stream periphyton may enter aquatic food chains through grazer ingestion. Hence, experiments were conducted to determine the ecotoxicological responses of the grazing mayfly Baetis tricaudatus to dietary cadmium. Short-term feeding experiments indicated that B. tricaudatus nymphs did not initially avoid grazing on cadmium-contaminated diatom mats. During a partial life-cycle experiment, 4 and 10 µg/g of dietary cadmium significantly inhibited grazing, whereas 10 µg/g significantly inhibited growth. Feeding inhibition was the likely mechanism that inhibited growth (i.e., through reduced energy intake). Conversely, when exposed to waterborne cadmium using lethal toxicity test procedures, B. tricaudatus nymphs were relatively tolerant (96-h median lethal concentration, 1,611 µg/L). Thus, sublethal responses to dietary exposure appeared to be more sensitive than lethal responses to waterborne exposure. Because adult mayfly fecundity is a function of nymph size at emergence, dietary cadmium exposure could increase the extinction probability within mayfly populations. The present study highlights the importance of dietary exposure routes in determining the ecotoxicological responses of an organism to a contaminant. Furthermore, the findings emphasize the advantage of evaluating a combination of ecologically relevant, lethal and sublethal endpoints in laboratory methods used to generate data for ecological risk assessment and regulation. "

Kiffney,PM and Clements,WH 1994 Effects of heavy metals on a macroinvertebrate assemblage from a Rocky Mountain stream in experimental microcosms. Journal of the North American Benthological Society 13 (4) 511-523.
     Insects were collected from artifical substrates left in the Big South Fork of the Cache la Poudre River draining the Front Range of Colorado. Riparian vegetation was Willow, Ponderosa, and Aspen (Salix spp. Pinus ponderosa and Populus tremuloides) at the collection site. B. tricaudatus and other aquatic insects were then subjected to one of 4 metal exposure treatments in the water of artifical streams at Colorado State University in Fort Collins, Colorado. B. tricaudatus densities were reduced at levels of 1 µg/l (1 microgram per liter) of Cadmium, 12 µg/l of Copper and 110 µg/l Zinc (all metals at the same time).

Kiffney,PM; Clements,WH 1996 Size-dependent response of macroinvertebrates to metals in experimental streams. Environmental Toxicology and Chemistry 15(8)1352-1356.
     Abstract: "Our previous research has shown that the effects of metals on stream benthic invertebrate populations and communities can vary within and between locations. With this in mind, we examined whether invertebrate body size could explain some of the variation in metal sensitivity within a species. Benthic macroinvertebrates from a pristine Rocky Mountain foothills' stream were collected using artificial substrates and exposed to a mixture of Cd, Cu, and Zn in stream microcosms for 10 d at their respective Colorado chronic criterion levels (4.0, 5.0, and 50 mu g/L). The effects of metals on the ephemeropterans Baetis tricaudatus (Baetidae), Ephemerella infrequens (Ephemerellidae), and Rhithrogena hageni (Heptageniidae) and the plecopteran Pteronarcella badia (Pteronarcyidae) were size dependent, as there was an inverse relationship between body size and survivorship. These results may have important implications for setting water-quality criteria for metals and For using benthic invertebrates in biological assessments. "

McCafferty,WP and Provonsha, AV The Mayflies of North AmericaSpecies List (Version 8Feb2011)
     Here is the geographic range and synonyms:
Baetis tricaudatus Dodds, 1923 [CAN:FN,NE,NW;MEX:FS,SW;USA:FN,NE,NW,SE,SW]
    Baetis incertans McDunnough, 1925 (syn.)
    Baetis intermedius Dodds, 1923 (syn.)
    Baetis jesmondensis McDunnough, 1938 (syn.)
    Baetis moffati Dodds, 1923 (syn.spell.)
    Baetis moffatti Dodds, 1923 (syn.)
    Baetis sp. No. 1 Traver, 1932 (syn.)
    Baetis parallelus Banks, 1924 (syn.)
    Baetis vagans McDunnough, 1925 (syn.)

Maret,TR; Cain,DJ; MacCoy,DE; Short,TM 2003 Response of benthic invertebrate assemblages to metal exposure and bioaccumulation associated with hard-rock mining in northwestern streams, USA. Journal of the North American Benthological Society 22 4, 598-620. Abstract and entire paper

McCafferty,WP; Durfee,RS; Kondratieff,BC 1993 Colorado mayflies (Ephemeroptera): an annotated inventory. Southwestern Naturalist 38 3, 252-274. PDF
     Quote from page 256: "This appears to be one of the most ubiquitous stream-dwelling mayfly species found in Colorado, and perhaps in North America (see Morihara and McCafferty, 1979b). It is known from many color and size variants that apparently may be correlated to a large extent with particular thermal growth regimes that vary with seaon and local, similar to that demonstrated experimentally in Stenacron and Hexagenia by McCafferty and Periera (1984) and also shown by Kondratieff and Voshell (1984) in field population variants of Isonychia. " The authors also mention at the end of their discussion of Faunisitics that B. tricaudatus is one of "those mayfly species that are truly widespread in North America"

McCafferty,WP and Provonsha, AV The Mayflies of North AmericaSpecies List (Version 12Jan2009)
     Here is the geographic range and synonyms:
Baetis tricaudatus Dodds, 1923 [CAN:FN,NE,NW;MEX:FS,SW;USA:FN,NE,NW,SE,SW]
    * Baetis incertans McDunnough, 1925 (syn.)
    * Baetis intermedius Dodds, 1923 (syn.)
    * Baetis jesmondensis McDunnough, 1938 (syn.)
    * Baetis moffati Dodds, 1923 (syn.spell.)
    * Baetis moffatti Dodds, 1923 (syn.)
    * Baetis sp. No. 1 Traver, 1932 (syn.)
    * Baetis parallelus Banks, 1924 (syn.)
    * Baetis vagans McDunnough, 1925 (syn.)

Mebane,CA; Dillon,FS and Hennessy,DP 2012 Acute toxicity of cadmium, lead, zinc, and their mixtures to stream-resident fish and invertebrates. Environmental Toxicology and Chemistry, 31(6), 1334-1348. PDF

Molles,MC and Pietruszka,RD 1983 Mechanisms of prey selection by predaceous stoneflies: roles of prey morphology, behavior and predator hunger. Oecologia 57(1) 25-31. Abstract

Morihara,DK; McCafferty,WP 1979 The Baetis larvae of North America (Ephemeroptera:Baetidae). Transactions of American Entomological Society 105, 139-221. PDF

Peckarsky,BL 1980 Influence of detritus on colonization of stream invertebrates. Canadian Journal of Fisheries and Aquatic Sciences 37, 957-963.

Riddell,DJ; Culp JM and Baird,DJ 2005 Behavioral responses to sublethal cadmium exposure within an experimental aquatic food web. Environmental Toxicology and Chemistry 24: 431-441.
     Abstract: " The foraging and predator-avoidance behaviors of mayfly (Baetis tricaudatus) nymphs and predator-prey interactions were investigated under differing combinations of cadmium concentration and predation risk. Predators consisted of stonefly (Kogotus nonus) nymphs, juvenile brook trout (Salvelinus fontinalis), and longnose dace (Rhinichthys cataractae), either alone or in combination. Organisms were exposed to 0, 0.5, or 5.0 µg/L Cd for 7 d (invertebrates) or 30 d (vertebrates) prior to observation in artificial stream channels. Behavioral observations (20-min duration) were made both day and night over a 24-h period. Mayfly feeding rate was assessed by image analysis of grazed diatom mats cultured on ceramic tiles. Both predators and cadmium produced significant effects on the behavior of B. tricaudatus and K. nonus nymphs, with mayflies showing a hierarchical response in the presence of multiple predators. A significant increase in activity was observed in S. fontinalis exposed to 5.0 ?g/L Cd, with significant decreases in capture efficiency of prey items apparent at 0.5 ?g/L Cd. Conversely, the foraging behavior of R. cataractae was unaffected by cadmium, possibly as a result of species-specific cadmium tolerance. Such sublethal effects of a contaminant on the energy budgets of individuals and the interactions between species have implications for community structure in aquatic food webs. "

Short,RA 1983 Food habits and dietary overlap among six stream collector species. Freshwater Invertebrate Biology 2:132-138. PDF

Stewart,KW and Szczytko,SW 1983 Drift of Ephemeroptera and Plecoptera in two Colorado rivers. Freshwater Invertebrate Biology. 2(3)117-131. PDF

The United States Geological Survey (USGS) National Water Quality Assessment Data Warehouse (NAWQA) shows this species is present in Gunnison County. Data as of 1Sep2005

Vieira,NK; Clements,WH; Guevara,LS and Jacobs,BF 2004 Resistance and resilience of stream insect communities to repeated hydrologic disturbances after a wildfire. Freshwater Biology, 49(10) 1243-1259. PDF
     Abstract: "1. Wildfires are often followed by severe, sediment-laden floods in burned catchments. In this study, we documented resistance and resilience of stream insect communities to repeated postfire flash floods in a 'burned stream'. We employed a before-after-control-impact (BACI) design, where communities in comparable reaches of a burned stream and a reference stream were sampled from 2 years before, to 6 years after, a crown wildfire in north-central New Mexico.
2. The first 100-year flood following the 1996 Dome wildfire reduced total insect density and taxon richness to near zero in the burned stream. Despite showing low resistance, density returned rapidly to prefire levels because of colonisation by simuliids, chironomids and the mayfly Baetis tricaudatus. In general, taxa that were generalist feeders (collectors) with strong larval dispersal dominated communities in early postfire years with repeated, moderate flash floods.
3. Taxon richness and community composition were less resilient to postfire hydrologic disturbances. Taxon richness did not recover until floods dampened 4 years after the fire. Despite hydrologic recovery, composition in the burned stream still differed from prefire and reference stream compositions after 6 years postfire. A unique assemblage, dominated by taxa with strong larval or adult dispersal, was established after flash floods abated. Specialist feeders (shredders and grazers) that were common in prefire years were reduced or absent in the postfire assemblage.
4. Community succession in the burned stream was explained by the interaction between species traits, geographic barriers to colonisation and hydrologic conditions after the fire. Comparable changes in insect density, taxon richness, community composition and trait representation were not found in the reference stream, providing strong evidence that repeated postfire flash floods shaped community responses in the burned stream. "

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

Webb,JM; Jacobus,LM; Funk,DH; Zhou,X; Kondratieff,BC; Geraci,CJ; DeWalt,RE Baird,DJ Richard,B Philips,I and Hebert,PDN 2012 A DNA barcode library for North American Ephemeroptera: Progress and prospects. PloS One 7(5): e38063 HTML
      Quote: " The non-monophyletic species are also likely species complexes as preliminary examination of some, such as Baetis tricaudatus Dodds, show morphological variation corresponding to barcode clusters. "

Williams,MC and Lichtwardt,RW 1999 Two new Harpellales living in Ephemeroptera nymphs in Colorado Rocky Mountain streams. Mycologia, 91(2) 400-404. PDF
     Abstract: "Two new species of harpellid gut fungi (Zygomycota: Trichomycetes) are described from the hindguts of mayfly nymphs inhabiting high altitude Rocky Mountain streams: the new genus and species Legeriosimilis tricaudata living in Ameletus sp. (Siphlonuridae), and the new species Glotzia coloradense from Baetis tricaudatus (Baetidae). Legeriomyces aenigmaticus is reported from a new site and a new ephemeropteran host, Ephemerella sp. (Ephemerellidae), and previously unknown zygospores are described."


The setae on the edges of the gills is fine and hard to spot on smaller nymphs. The edges of the gills are serrated too. See Baetis magnus

Brown, WS 2004 Mayflies (Ephemeroptera) of Gunnison County, Colorado, USA