Trichoptera: Hydropsychidae of Gunnison County, ColoradoHydropsyche oslariBanks, 1905Updated 26 March 2026
NotesCommon across western North America.Good LinksOn this website:Hydropsyche Introduction Other Websites: Photos, Map, Taxon Identifier Numbers - from the Global Biodiversity Information Facility Hydropsyche oslari at GBIF Illustration - University of Alberta Entomology Collection Species page Has description, habitat information, range and more. North American distribution map - flyfishingentomology.com ReferencesAlstad,DN 1980 Comparative biology of the common Utah Hydropsychidae (Trichoptera). American Midland Naturalist 103, 167-174.Anderson,NH 1976 The distribution and biology of Oregon Trichoptera. Agricultural Experiment Station, Oregon State University. Technical Bulletin, 134. PDF  Banks,N 1905 Descriptions of new neuropteroid insects. Transactions of American Entomological Society 32, 1-20.  
Balistrieri,LS; Mebane,CA and Schmidt,TS 2020 Time-dependent accumulation of Cd, Co, Cu, Ni, and Zn in mayfly and caddisfly larvae in experimental streams: Metal sensitivity, uptake pathways, and mixture toxicity. Science of the Total Environment, 732. html 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,FCJ 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 1988 Competition between two stream dwelling filter-feeders, Hydropsyche oslari and Simulium virgatum. Oecologia, 77, pp.73-80. Abstract: "This study investigated whether interspecific competition affected the abundance and distribution of Hydropsyche oslari and Simulium virgatum. In addition, I studied the mechanisms of competition between the two taxa. H. oslari was the superior competitor when compared to S. virgatum because the presence of H. oslari in boulder habitats in Refugio Creek altered the microdistribution and depressed numbers of S. virgatum. Hydropsyche preempted space and was aggressive towards Simulium. Simulium avoided both hydropsychid larvae and their nets. This avoidance behaviour was reinforced by aggression from H. oslari. Possible immediate reasons why simuliids avoided Hydropsyche nets included 1) Hydropsyche attacked Simulium, 2) occupied nets interfered with feeding through increased turbulence or lower renewal rate for food, and 3) Simulium preferred to settle with conspecifics." Hemphill,N 1991 Disturbance and variation in competition between two stream insects. Ecology 72 (3) 864-872. Abstract: "This study examined temporal and spatial variability in competition as well as the relative importance of competition and natural disturbance to Hydropsyche oslari and Simulium virgatum in a southern California stream. These two filter-feeding insects dominated the community studied, accounting for 99% of all individuals. I maintained four field treatments every 2 wk for a year: (1) removal of Simulium; (2) removal of Hydropsyche; (3) removal of both taxa and subsequent scrubbing of the rock surfaces; and (4) unmanipulated controls. Competition from Hydropsyche oslari restricted the spatial distribution of Simulium virgatum in all seasons except late winter in upstream but not in downstream sections of the study site. Downstream abundance of Simulium was probably limited by food availability, not competition from Hydropsyche. During the winter, when floods occurred and densities were low, competition between these insects had no significant impact on spatial distributions. Although competition was seasonally variable, it occurred frequently and was not rare. Although disturbance mediated competition, competition was more important in determining the abundance of Simulium in 1983-1984, a drought year. Disturbance caused a 13% increase, while competition caused a 34% decline in the simuliid population over the year. It was not possible, however, to rank the importance of competition and disturbance when considering both species together. The relative importances were taxon specific. The abilities of Simulium and Hydropsyche to recover quickly after disturbance were inversely related to their ability to withstand competition. In addition, the interaction between the two factors was extremely important in determining the relative abundance of both taxa through the year. Competition and disturbance both played an important role in regulating this community, at times accounting for up to 60% reductions in the numbers of individuals present in the stream. The relative importance of competition and disturbance in Refugio Creek should vary from year to year depending on the timing and intensity of winter storms." Hemphill,N and Cooper,SD 1983 The effect of physical disturbance on the relative abundances of two filter-feeding insects in a small stream. Oecologia, 58 378-382. PDF Abstract: "We examined the importance of disturbance in determining the relative abundances of two lotic filter-feeders, Simulium virgatum and Hydropsyche oslari, in a small, coastal stream in southern California, USA.In most years, winter spates effectively scour substrata in fast-flowing areas, thereby drastically reducing stream insect populations. Newly-opened space in these areas is quickly colonized by simuliids. The abundance of simuliids, however, gradually declines as hydropsychid abundance increases in early summer. To determine if these changes in insect abundance represent seasonal changes or successional changes following disturbance, we performed a field experiment where hard substrates were disturbed at 2 wk, 4 wk, or 8 wk intervals, or were left undisturbed. We found that the numbers of simuliids increased and the numbers of hydropsychids decreased as the frequency of disturbance increased. Although seasonal recruitment patterns and longitudinal position in the strem had important effects on the colonization rates of these insects, time since last disturbance was a prime determinant of the relative abundances of Simulium and Hydropsyche. These results and additional observations suggest that Simulium virgatum is an opportunistic species that quickly colonizes new space, but that it is displaced by the slower-colonizing but competitively superior Hydropsyche oslari. Disturbance promotes the coexistence of these two species by preventing the attainment of a climax state where Hydropsyche monopolizes available space. " 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.309-320. 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 and 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 and 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-). " 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. U.S. Geological Survey Data Series 606, 257 p. PDF - caution 46MB Quote from page 71: "This species is another widely distributed and common western montane Hydropsychid (Schefter and others, 1986; Wiggins and Parker, 1997)." The elevation range is 4,800-9,600 feet and the adults emerge from April-September. |