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Trichoptera: Hydropsychidae of Gunnison County, Colorado

Hydropsyche oslari

Banks, 1905
Updated 22 March 2023


Common across western North America.

Good Links

On this website:
Hydropsyche Introduction

Other Websites:
Illustration - University of Alberta Entomology Collection Species page
     Has description, habitat information, range and more.

North American distribution map - flyfishingentomology.com


Alstad,DN 1980 Comparative biology of the common Utah Hydropsychidae (Trichoptera). American Midland Naturalist 103, 167-174.

Banks,N 1905 Descriptions of new neuropteroid insects. Transactions of American Entomological Society 32, 1-20.
Nathan Banks 1905 description of the caddisfly Hydropsyche oslari
Nathan Banks 1905 drawing of the male genitalia of the caddisfly Hydropsyche oslari Nathan Banks 1905 figure legend for the male genitalia of the caddisfly Hydrospyche oslari

Buchwalter,DB; Luoma,SN 2005 Differences in dissolved cadmium and zinc uptake among stream insects: mechanistic explanations. Environmental Science and Technology 39, 498-504.

Canton,SP and Ward,JV 1981 The aquatic insects, with emphasis on Trichoptera, of a Colorado stream affected by coal strip-mine drainage. Southwestern Naturalist 25 4, 453-460.
     They studied Trout Creek where it runs through the Edna Coal Mine in northwestern Colorado. The mine spoils were 30 meters from the edge of the creek (approximately a 100 foot buffer zone). They found the aquatic insect density (numbers per square meter) and biomass (weight in grams per square meter) did not change above and below the mine. The Shannon-Weaver Diversity index also showed no difference between sites. However the community structure (which species were present and proportions) did change. Since there were irrigation water and cattle influences at their downstream site, their results may reflect these additional water uses. They note the biggest visible change at this mine is the loss of willow and alder trees downstream of the mine. The caddisfly population changed the most between sites, shifting from a mix of families above the mine to dominance by Hydropsychidae and Glossosomatidae below the mine.
Quote from page 457: "The Hydropsychidae (Arctopsyche inermis, Hydropsyche cockerelli, and H. oslari) were unimportant at C2 (reference site), comprising only 3% of trichopteran numbers, while at C4 (mine affected), with increased abundance of Hydropsyche spp., they accounted for 16% of the density."

Djernæs,M and Sperling,FAH 2012 Exploring a key synapomorphy: correlations between structure and function in the sternum V glands of Trichoptera and Lepidoptera (Insecta). Biological Journal of the Linnean Society, 106: 561-579.

Erman,NA 1989 Species composition, emergence, and habitat preferences of Trichoptera of the Sagehen Creek Basin, California, USA. The Great Basin Naturalist, 186-197. PDF
     Quote from page 192: "It is apparent that certain species are ubiquitous in western North America (i.e., Hydropsyche oslari, Polycentropus halidus, Rhyacophila vao), and others are probably confined to a small area in the Sierra Nevada. " Fischer, F.C.J. 1960-1973. Trichopterorum Catalogus, volumes I-XV and Index. Nederlandsche Entomologische Vereeniging, Amsterdam.

Gray,LJ and Ward,JV 1979 Food habits of stream benthos at sites of differing food availability. American Midland Naturalist 102 1, 157-167.

Hemphill, N. 1991 Disturbance and variation in competition between two stream insects. Ecology: Vol. 72, No. 3, pp. 864-872. Abstract

Herrmann,SJ 1990 New record and range extension for Rhyacophila wallowa (Trichoptera: Rhyacophilidae) from Rocky Mountain National Park, Colorado. Entomological news (USA).
     While studying R. wallowa, the author found H. oslari adults near the cold streams Fall River and Chiquita Creek at 2640m or 8660ft amsl in Rocky Mountain National Park in Colorado.

Herrmann,SJ; Ruiter,DE and Unzicker,JD 1986 Distribution and records of Colorado Trichoptera. Southwestern Naturalist 31 4, 421-457.
     They note the habitat for this species is streams and rivers, the altitudinal range is 1615 to 2895m and adult collection dates are 10 June to 1 September. Quote from page 429: "Fisher (1960-1973) reported the geographical range from British Columbia to California and East to New Mexico and Utah." They list this species as present in Gunnison county.

Hauer,FR and Stanford,JA 1982 Ecology and life histories of three net-spinning caddisfly species (Hydropsychidae: Hydropsyche) in the Flathead River, Montana. Freshwater Invertebrate Biology 1:18-29.
     They present life history data on the three species H. cockerelli, H. oslari and H. occidentalis in the tailwaters of Hungry Horse Dam. Quotes from the abstract "H. cockerelli and H. oslari were significantly (P < 0.05) more abundant than H. occidentalis at all sampling sites. H. oslari larvae, although present in early instars during autumn, remained in early instars through the winter months and grew during spring. Adults emerged during late June and July."

Metcalfe,AN; Kennedy,TA; Marks,JC; Smith,AD and Muehlbauer,JD 2020 Spatial population structure of a widespread aquatic insect in the Colorado River Basin: Evidence for a Hydropsyche oslari species complex. Freshwater Science, 39(2), pp.000-000. PDF
     Abstract: "Structural connectivity and dispersal ability are important constraints on functional connectivity among populations. For aquatic organisms that disperse among stream corridors, the regional structure of a river network can, thus, define the boundaries of gene flow. In this study, we used mitochondrial DNA (mtCO1 barcoding gene) to examine the genetic diversity and population structure of a caddisfly with strong dispersal capabilities, Hydropsyche oslari (Trichoptera:Hydropsychidae), in the topologically-diverse Colorado River Basin. We expected to find less genetic differentiation among populations of H. oslari within the Upper Basin, which has a dense dendritic network of perennial tributaries that allow for greater potential dispersal and gene flow, than among populations within the arid and sparse river network of the Lower Basin. We also expected to find genetic differentiation among H. oslari in the Upper and Lower Basins because contemporary populations are geographically distant from each other and have been separated by a >300-km-long reservoir (Lake Powell) for half a century. Consistent with these predictions, we found that populations of H. oslari within the Upper Basin had more shared haplotypes and less nucleotide diversity (ℼ = 0.001-0.008) than H. oslari within the Lower Basin (FST = 0.01, ℼ = 0.014-0.028). However, populations were genetically more structured in the Upper Basin (FST = 0.47) than in the Lower Basin (FST = 0.01). We also found that populations in the Upper and Lower Basin are entirely genetically differentiated (Snn = 1), suggesting that these 2 populations were isolated thousands of years before the 1963 closure of Glen Canyon Dam and subsequent filling of Lake Powell. The most similar haplotypes among the 2 basins represent a 5.4% difference, which indicates the presence of a species complex within H. oslari."

Metcalfe,AN; Muehlbauer,JD; Kennedy,TA; Yackulic,CB; Dibble,KL and Marks,JC 2021 Net-spinning caddisfly distribution in large regulated rivers. Freshwater Biology, 66(1)89-01 PDF
     Abstract: "1. Most of the world's large rivers are dammed for the purposes of water storage, flood control, and power production. Damming rivers fundamentally alters water temperature and flows in tailwater ecosystems, which in turn affects the presence and abundance of downstream biota.
2. We collaborated with more than 200 citizen scientists to collect 2,194 light trap samples across 2 years and more than 2,000 river km. Samples contained 16,222 net-spinning caddisfly (Hydropsyche) individuals across six species. We used these data to model the distribution of Hydropsyche throughout the Colorado River Basin in the western U.S.A. to identify the roles of water temperature, flows, and species-specific morphology in determining aquatic species distributions throughout a large arid watershed that has been heavily altered by damming.
3. We predicted that water temperatures would determine Hydropsyche presence and abundance to a greater extent than diel variation in river stage associated with hydropower production. Among many species, adult female Hydropsychids are morphologically adapted to swim to deep-water oviposition sites. We predicted that the presence of this ability would negate the otherwise deleterious effects of high stage change on caddisfly egg mortality.
4. We found that distributions of the two most widespread species, Hydropsyche occidentalis and Hydropsyche oslari (92% of total Hydropsyche captured), were both predicted by water temperatures. However, we also found that the abundance of H. oslari decreased by as much as 10-fold as diel stage change increased, despite the presence of female morphological adaptations for deep-water oviposition. We found sexual dimorphism and evidence for deep-water swimming adaptations in 5/6 species.
5. Our results show that net-spinning caddisflies have species-specific responses to environmental variation and suggest that environmental flows designed to reduce diel stage change and destabilise water temperatures may improve habitat quality for these ubiquitous and important aquatic insects."

Nimmo,AP 1987 The adult Arctopsyche and Hydropsyche (Trichoptera) of Canada and adjacent United States. Questiones Entomologicae 23:1-189.

Perry SA; Perry WB; Stanford JA. 1986 Effects of stream regulation on density, growth, and emergence of two mayflies (Ephemeroptera: Ephemerellidae) and a caddisfly (Trichoptera: Hydropsychidae) in two Rocky Mountain rivers (U.S.A.). Canadian Journal of Zoology 64(3):656-666.

del Rosario,RB; Betts,EA; Resh,VH 2002 Cow manure in headwater streams: tracing aquatic insect responses to organic enrichment. Journal of the North American Benthological Society (21)278-289

Schefter,PW and Wiggins,GB 1986 A systematic study of the nearctic larvae of the Hydropsyche morosa group (Trichoptera: Hydropsychidae). Life Sciences Miscellaneous Publications of the Royal Ontario Museum.

Serrana,JM; Li,B; Sumi,T; Takemon,Y and Watanabe,K 2022 Implications of taxonomic and numerical resolution on DNA metabarcoding-based inference of benthic macroinvertebrate responses to river restoration. Ecological Indicators, 135, p.108508. HTML
     Quote: "At the species level with the metabarcoding dataset, six species, i.e., Wormaldia gabriella, Attenella margarita, Haemaphysalis flava, Rhyacophila malkini, Ordobrevia nubifera, and Hydropsyche oslari were identified as indicators with significant associations with the non-dam impacted sites (DAM-GB + and DAM-GB-). "

Brown,WS 2005 Trichoptera (Caddisflies) of Gunnison County, Colorado, USA