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Ephemeroptera: Ephemerellidae of Gunnison County, Colorado

Drunella coloradensis
Slate-Winged Olive, Small Western Green Drake

(Dodds) 1923
Updated 8 Oct 2020
TSN 101389

Notice the "tubercles" on the front legs. That is a trait used to identify the genus Drunella. Look for the absence of gills on the first two abdominal segments. That indicates this larvae is in the mayfly family Ephemerellidae.

Also note the striped tails on this D. coloradensis larvae. Caught and released in the Upper East river, early August 2011.

Good Links

On this website:
Drunella Introduction

Other Websites:


Allan,JD 1981 Determinants of diet of brook trout (Salvelinus fontinalis) in a mountain stream. Canadian Journal of Fisheries and Aquatic Sciences 38, 184-192. PDF

Allan,JD 1985 The production ecology of Ephemeroptera in a Rocky Mountain stream. Internationale Vereinigung für Theoretische und Angewandte Limnologie Verhandlungen 22, 3233-3237.

Allan,JD 1987 Macroinvertebrate drift in a Rocky Mountain stream. Hydrobiologia 144, 261-268.

Allen,RK and Edmunds,GF 1962 A revision of the genus Ephemerella (Ephemeroptera: Ephemerellidae). V. The subgenus Drunella in North America. Miscellaneous Publications of the Entomological Society of America 3, 147-179. PDF

Dahl, J and Peckarsky, BL 2003 Does living in streams with fish involve a cost of induced morphological defences? Canandian Journal of Zoology. 81(11): 1825-1828. PDF
     Abstract: " Phenotypic plasticity may enable organisms to optimize their phenotypes in environments that are heterogeneous over time or space. For example, inducible defenses are favored for prey populations faced with variable predation risk. We studied the impact of brook trout (Salvelinus fontinalis) on the development of defensive morphological characters in larvae of the mayfly, Drunella coloradensis, both in natural streams and in a series of experiments carried out in streamside, circular, flow-through chambers. Drunella larvae in natural streams with trout had longer caudal filaments per unit body size and relatively heavier exoskeletons than Drunella in fishless streams. Female larvae that developed in fish streams were also significantly smaller and less fecund at metamorphosis than those living in fishless streams, suggesting a possible fitness cost associated with development of morphological defenses. However, timing of metamorphosis of Drunella larvae to the adult stage did not differ between fish and fishless streams.
Larvae originating from fish and fishless streams were reared and exposed to water with fish cues or fishless control water for three weeks (1998) or until they developed black wing pads, i.e., just before emergence (1999). In both experiments waterborne fish cues induced the development of relatively longer caudal filaments, but only in Drunella originating from sites without fish. Waterborne fish cues had no effect on Drunella growth rates, behavior, or size at emergence. Drunella originating from fish streams had significantly lower mortality when exposed to predation by trout than Drunella originating from fishless streams. Caudal filament length appears to enhance survival, as Drunella with intact caudal filaments had lower predation rates than Drunella with their tails artificially shortened. This study provides evidence of chemically induced morphological plasticity that could reduce predation rates of these mayflies in natural stream environments."

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

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 Ephemerella (Drunella) coloradensis.

Hawkins,CP 1985 Food habits of species of ephemerellid mayflies (Ephemeroptera: Insecta) in streams of Oregon. American Midland Naturalist 113(2) 343-352. PDF

McCafferty,WP; Durfee,RS; Kondratieff,BC 1993 Colorado mayflies (Ephemeroptera): an annotated inventory. Southwestern Naturalist 38 3, 252-274. PDF
     Quote from page 264-265: "Prior to 1987 this species was reported as Ephemerella coloradensis. ...This common western species ranges from Arizona to Alaska. "

Dahl,J and Peckarsky,BL 2002. Induced morphological defenses in the wild: predator effects on a mayfly, Drunella coloradensis. Ecology 83:1620-1634. Abstract

McCafferty,WP and Provonsha, AV The Mayflies of North America Species List (Version 8Feb2011)
     Here is the geographic range and synonyms:
Drunella coloradensis (Dodds), 1923 [CAN:FN,NW;MEX:SW;USA:FN,NW,SW]
    * Ephemerella coloradensis Dodds, 1923 (orig.)
    * Ephemerella wilsoni Mayo, 1952 (syn.)

Mihuc,TB and Minshall, GW 1995 Trophic generalists vs. trophic specialists: implications for food web dynamics in post-fire streams. Ecology, 76(8), pp.2361-2372.
     Abstract: "The trophic ecology of 11 benthic macroinvertebrate taxa found in Cache Creek, Yellowstone National Park (YNP) was studied to determine if burned organic matter is an important resource and how resource utilization patterns may be altered in post-fire streams. Laboratory food quality experiments were conducted to determine the growth response of each species when grown on several resource types: burned organic matter, periphyton, unburned coarse particulate material (CPM), and unburned fine particulate material (FPM). The central hypothesis of this research was that benthic macroinvertebrates cannot use burned organic matter as a resource. A secondary hypothesis was that some benthic macroinvertebrates are facultative in trophic function, with the ability to use both allochthonous and autochthonous resources for growth. Of the 11 taxa studied, only one (Paraleptophlebia heteronea) could grow on burned organic matter as a resource, indicating that post-fire food webs probably do not exhibit major shifts in resource utilization to burned material. Two species were generalist detrivores (P. heteronea, Ameletus cooki) able to use both natural FPM and CPM resources. Two species were specialist detritivores (Oligophlebodes sigma, Ephemerella infrequens) growing only on unburned CPM resources, and two (Cinygmula mimus, Epeorus albertae) were specialist herbivores utilizing only periphyton. Five species were generalist herbivore-detritivores (Baetis bicaudatus, Drunella doddsi, D. coloradensis, D. spinifera, Zapada columbiana), exhibiting growth on both detritus and periphyton resources. Based on the experimental results, trophic generalists are common food web components in Yellowstone streams. Two of the most abundant benthic macroinvertebrates during post-fire recovery, B. bicaudatus and Z. columbiana, were trophic generalists, indicating that some generalists may be disturbance adapted. In this study, published functional feeding group classification did not indicate obligate resource utilization (growth on only one resource type) for most taxa studied. Comparison of a food web for Cache Creek based on functional feeding group classification and one based on the results of this study indicates that the inclusion of generalists in the web results in a more realistic approximation of food web relationships such as the link-species scaling law. Our results suggest that future research should include spatial and temporal aspects of resource switching and generalist resource utilization by individual lotic primary consumers."

Pennuto,CM and deNoyelles Jr,F 1993 Behavioral responses of Drunella coloradensis (Ephemeroptera) nymphs to short-term pH reductions. Canadian Journal of Fisheries and Aquatic Sciences 50, 2692-2697.

Ward,JV and Berner,L 1980 Abundance and altitudinal distribution of Ephemeroptera in a Rocky Mountain stream. In Advances in Ephemeroptera biology (pp. 169-177). Springer US. PDF
     Discussed as Ephemerella coloradensis.

Wellnitz,T 2014 Can current velocity mediate trophic cascades in a mountain stream?. Freshwater Biology, 59(11) 2245-2255. PDF

Winget,RN and Mangum,FA 1996 Environmental profile of Drunella coloradensis Dodds (Ephemeroptera: Ephemerellidae) in the Western United States. Journal of Freshwater Ecology 11 2, 225-232.
     Abstract: "We describe several niche dimensions of Drunella coloradensis Dodds based upon physical and chemical parameters of over 900 stream stations in 11 western states. Nymphs were found at 199 stations and were collected at elevations from near sea level to over 9,000 ft and from streams with a wide range of water discharges. This mayfly showed significant avoidance of streams with <l% channel gradients and those where fine sediments dominated the substrate. Nymphs of D. coloradensis selected for waters with <100 mg/l alkalinity and <50 mg/l sulfate and streams with brush or evergreen trees dominating the riparian vegetation. Drunella coloradensis is intolerant of water quality degradation but moderately tolerant of other changes in the physical habitat. Drunella coloradensis shows divergence from related species through resource partitioning strategies related to water quality tolerances and physical habitat selection."

Drunella coloradensis larvae from the Upper East river in early August 2011.

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