Stoneflies - Plecoptera: Capniidae of Gunnison County, Colorado
Capnia confusa Claassen 1936
Widespread Snowfly, Winter Stonefly
Updated 21 January 2021
This winter stonefly is common and widespread. Nelson and Baumann comment that C. confusa is "responsible for the wide distributional range of this genus."
Usually found on the snow in mid to late winter in the East and Gunnison River drainages.
On this website:
Photos, Map, Museum specimens, DNA - Barcodinglife.org
Baumann,RW, Gaufin,AR and Surdick,RF 1977 The stoneflies (Plecoptera) of the Rocky Mountains. Memoirs of the American Entomological Society 31, 1-208.
Quoted from page 68: "This species occurs commonly in creeks,with the adults emerging from February to June."
Claassen,PW 1936 New names for stoneflies (Plecoptera). Annals of the Entomological Society of America 29: 622-623.
Clements,W; Stahl Jr,RG and Landis,RC 2015 Ecological effects of biochar on the structure and function of stream benthic communities. Environmental science & technology, 49(24), pp.14649-14654.
Abstract: "The introduction of biochar, activated carbon, and other carbonaceous materials to aquatic ecosystems significantly reduces the toxicity and bioavailability of contaminants. However, previous studies have shown that these materials can have negative effects on aquatic organisms. We conducted field and mesocosm experiments to test the hypothesis that biochar altered the structure and function of stream benthic communities. After 30 d in the field, colonization by stoneflies (Plecoptera) was significantly lower in trays containing biochar compared to the results from the controls. In stream mesocosms, biochar increased macroinvertebrate drift and significantly reduced community metabolism. However, most measures of community composition showed little variation among biochar treatments, and significant responses were limited to a single stonefly species (Capnia confusa). When benthic communities were simultaneously exposed to biochar and Cu, effects were primarily associated with metal exposure. Because it is unlikely that biochar treatments would be employed in uncontaminated areas, these moderately negative effects should be considered within the context of the positive benefits associated with reduced contaminant bioavailability and toxicity. Additional research is necessary to improve our understanding of the mechanisms responsible for biochar effects on benthic communities and to identify the optimal application rates and size fractions that will maximize contaminant sorption but minimize potential negative effects."
Donald,DB and Patriquin,DE 1983 The wing length of lentic Capniidae (Plecoptera) and its relationship to elevation and Wisconsin glaciation. The Canadian Entomologist, 115(8) 921-926.
Abstract: "Along the Continental Divide in Alberta, British Columbia, and Montana three species of Capniidae were common at some lakes (Capnia confusa Claassen, Isocapnia integra Hanson, and Utacapnia trava (Nebeker and Gaufin)). Females of all three species had substantial reduction in wing length at least at one lake, while most lentic populations had slightly shorter wings than a macropterous river population of the same species. For females of all three species there was a weak positive relationship between functional wing length and lake elevation. Furthermore, there was also a significant negative relationship between functional wing length and the approximate year of Wisconsin deglaciation for C. confusa and U. trava. Suitable data were not available to test the significance of this relationship for I. integra. However, the relationships between wing length and elevation, and between wing length and Wisconsin deglaciation, suggest that wing length of these three capniid species is related to lake age. Present day wing length might be explained by selection for brachypterism over recent millennia."
Dosdall,LM and Lehmkuhl,DM 1979 Stoneflies (Plecoptera) of Saskatchewan. Quaestiones Entomologicae.
Duffield,RM and Nelson,CH 1998 Stoneflies (Plecoptera) in the diet of brook trout (Salvelinus fontinalis Mitchell) in Libby Creek, Wyoming, USA. Hydrobiologia 380, 59-65.
Although collected as adults in the streamside vegetation, Capnia confusa adults were not found in the stomach contents of the trout living in the stream. However, some larvae were found in trout gut contents.
Kondratieff,BC and Baumann,RW 2002 A review of the stoneflies of Colorado with description of a new species of Capnia (Plecoptera: Capniidae). Transactions of American Entomological Society 128 3, 385-401.
Quote from page 388: " This later emerging winter stonefly (March to July) is one of the widespread and common stonefly species in Colorado. Capnia confusa adults can be found abundantly emerging from medium to large sized streams ranging in elevation from 1,520 m to 3,860 m. Adults are sometimes still active as late as July at higher elevation streams."
Nelson,RC and Baumann,RW 1989 Systematics and distribution of the winter stonefly genus Capnia (Plecoptera: Capniidae) in North America. Great Basin Naturalist 49 289-363. PDF
They placed C. confusa in the Vernalis Group. They comment "this is probably the most widespread member of the genus in North America"
Newell,RL; Baumann,RW and Stanford,JA 2008 Stoneflies of Glacier National Park and Flathead River basin, Montana. International Advances in the ecology, zoogeography, and systematics of mayflies and stoneflies. University of California Publications in Entomology, Berkeley and Los Angeles, pp.173-186. PDF
Quote from page 176: "Stoneflies recorded from hyporheic habitats (pumped wells) included: Alloperla severa, Capnia confusa, Claassenia sabulosa, Diura knowltoni, Hesperoperla pacifica, Isocapnia crinita, I. grandis, I. integra, I. vedderensis, Isoperla fulva, Kathroperla, Paraperla frontalis, and P. wilsoni"
Radford,DS and Hartland-Rowe,R 1971 Emergence patterns of some Plecoptera in two mountain streams in Alberta. Canadian Journal of Zoology, 49(5), 657-662.
Ruse,LP and Herrmann,SJ 2000 Plecoptera and Trichoptera species distribution related to environmental characteristics of the metal-polluted Arkansas River, Colorado. Western North American Naturalist 60 (1) 57-65. PDF
They looked at the Arkansas River above and below some notorious heavy metal mine pollution sources, California Gulch and the Leadville Drain. They found that adult C. confusa were eliminated by the Leadville Drain, recovered and reappeared a ways downstream, then were gone below California Gulch. After freshwater was added to the Arkansas River from the western slope, they reappeared at one site. They were probably missing farther downstream due to warmer water temperatures and would have been missing from a clean river as well.
Short,RA; Canton,SP and Ward,JV 1980 Detrital processing and associated macroinvertebrates in a Colorado mountain stream. Ecology, 61(4), 727-732. PDF
Capnia confusa nymphs were found in all 4 of the plant species used to make leaf packs; alder, willow, aspen and pine.
Short,RA; Ward,JV 1981 Trophic ecology of three winter stoneflies (Plecoptera). American Midland Naturalist 105, 341-347.
Abstract: " Winter stoneflies (Zapada oregonensis, Z. cinctipes and Capnia confusa) used detritus as a nymphal food almost exclusively and dominated the shredder biomass in a third-order mountain stream in Colorado. Laboratory feeding trials showed that ingestion rates and fecal production were temperature-dependent, although not greatly different between aspen or alder leaf discs. Assimilation efficiency (AE) was not temperature-dependent. Higher AE values for alder indicate that it is superior to aspen as a food source. High consumption rates (ca. 30% of body weight/day) by the shredders, even at low temperatures, would result in the conversion of considerable quantities of leaf litter to finer particles. However, size fraction analysis of egested material indicated that particle size reduction by shredder processing only partially explains detrital composition in a stream dominated by fine-particle feeding detritivores."
Zuellig,RE; Heinold,BD; Kondratieff,BC and Ruiter,DE 2012 Diversity and distribution of mayflies (Ephemeroptera), stoneflies (Plecoptera), and caddisflies (Trichoptera) of the South Platte River Basin, Colorado, Nebraska, and Wyoming, 1873-2010 (No. 606). US Geological Survey. PDF - caution 46MB
Elevation collected 4,950-10,500ft Adults were found February-July. Remarks from page 38: "This is one of the most common and widespread species of the genus Capnia (Kondratieff and Baumann, 2002). It also has one of the latest emerging periods of winter stoneflies with females present from February into July (Nelson and Baumann, 1989). Records for this species were available from small high and low elevation streams ranging from 10,500 to 4,950 ft in elevation."
Brown, WS 2004 Plecoptera or Stoneflies of Gunnison County, Colorado
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