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Trichoptera: Brachycentridae of Gunnison County, Colorado

Brachycentrus occidentalis
Early grannom, Mother's Day Caddis

Banks 1911
Updated 17 May 2017
TSN 116918

Good Links

On this website:
Brachycentrus americanus

Other Websites:
Photos, Map, Museum specimens, DNA - Barcodinglife.org

Photo - from Midwest Fly Fishing Online http://www.mwfly.com/pages/ento.html

Arkansas River Hatch - from the Denver Post http://www.denverpost.com/news/ci_3700264

Yellowstone River Hatch - The Mother's Day Hatch http://www.yellowstoneflyfishing.com/caddisflies.htm
     After a good discussion of fishing and caddisfly hatches they talk about B. occidentalis partway down the page.

Illustration - University of Alberta Entomology Collection Species page
     Has illustration of male genitalia, description, habitat information, range and more.


Banks,N 1911 Descriptions of new species of North American Neuropterid Insects. Transactions of American Entomological Society 37, 335-360.
     Describes this species on page 355, and illustrates it on plate 13 and figure 32.

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.

Flint,OS, Jr. 1984 The genus Brachycentrus in North America, with a proposed phylogeny of the genera of Brachycentridae (Trichoptera). Smithsonian Contributions to Zoology 398:1-58. PDF
     The author studied larval specimens from the Black Canyon of the Gunnison in Montrose County.

Flint,OS, Jr. 1984. On the genus Brachycentrus (abstract). Pages 143 in Proceedings of the 4th International Symposium on Trichoptera (J. C. Morse, ed.) Dr. W. Junk, The Hague.

Gallepp,GW 1974 Behavioral ecology of Brachycentrus occidentalis Banks during the pupation period. Ecology, Vol. 55(6) 1283-1294. Abstract and first page

Gallepp, G. W., Jr. 1975 The behavioural ecology of larval caddisflies, Brachycentrus americanus and Brachycentrus occidentalis. Dissertation Abstracts International 35: 4532.

Gallepp, G. 1976 Temperature as a cue for the periodicity in feeding of Brachycentrus occidentalis (Insecta: Trichoptera). Animal Behaviour 24: 7-10.

Gallepp,GW 1977 Responses of caddisfly larvae (Brachycentrus spp.) to temperature, food availability and current velocity. American Midland Naturalist 98(1)59-84. Abstract

Gaufin,AR; Clubb,R and Newell,R 1974 Studies on the tolerance of aquatic insects to low oxygen concentrations. Great Basin Naturalist 34:45-59. PDF
      The authors studied the acute short term tolerance of aquatic insects to low oxygen. They used the 96 hour Median Tolerance Limit. They did not find a TLm96 for B. occidentalis. The authors had 90% survival from 2-4 mg/l oxygen with their experimental apparatus.

Gaufin,AR and Hern,S 1971 Laboratory studies on tolerance of aquatic insects to heated waters. Journal of the Kansas Entomological Society 44:240-245. PDF
     Abstract: "The mature larvae of fifteen species of aquatic insects (Diptera, Ephemeroptera, Plecoptera, and Trichoptera) and the scud (Amphipoda) were tested to determine their relative sensitivity to heated waters under laboratory conditions. The temperature at which 50% died after 96 hours (TLm96) was recorded as the lethal temperature. This ranged from 11.7 C for the torrential stream mayfly, Cinygmula par Baton, to 32.6 C for the snipefly, Atherix variegata Walker. "       The TLm96 for B. occidentalis was 29.7°C.

Hauer,FR; Stanford,JA 1986 Ecology and co-existence of two species of Brachycentrus (Trichoptera) in a Rocky Mountain River. Canadian Journal of Zoology 64 7, 1469-1474.

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 2926m and adult collection dates are 16 April to 6 July. Quote from page 425: "In Colorado this species is usually more common below 1829m while B. americanus more common above 1829m; B. occidentalis also seems to ewerge earlier." They list this species as present in Gunnison county.

Hauer,FR and Stanford,JA 1986 Ecology and co-existence of two species of Brachycentrus (Trichoptera) in a Rocky Mountain River. Canadian Journal of Zoology 64 7, 1469-1474.
     Studying the Flathead River of Montana for three years, the authors found that B. occidentalis larvae appeared as early instar larvae in mid to late summer and overwintered as 4th or 5th instar larvae. They were active until spring runoff and pupated in May and June. B. occidentalis emerged as adults during August and September. They avoided competition with Brachycentrus americanus larvae by slightly staggered life cycles, with adults of B. americanus emerging in late summer and early fall.

Hauer,FR; Stanford,JA and Ward,JV 1989 Serial discontinuities in a Rocky Mountain river. II. Distribution and abundance of Trichoptera. Regulated Rivers: Research and Management 3, 177-182.

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

Voelz,NJ and Ward,JV 1996a Microdistributions, food resources and feeding habits of filter-feeding Trichoptera in the Upper Colorado River. Archiv fur Hydrobiologie 137 3, 325-348.

Voelz,NJ and Ward,JV 1996b Microdistributions of filter-feeding caddisflies (Insecta:Trichoptera) in a regulated Rocky Mountain river. Canadian Journal of Zoology 74, 654-666.

Voelz,NJ; Poff,NL and Ward,JV 1994 Differential effects of a brief thermal disturbance on caddisflies (Trichoptera) in a regulated river. American Midland Naturalist 132 1, 173-182. Abstract

Wetmore,SH; Mackay,RJ and Newbury,RW 1990 Characterization of the hydraulic habitat of Brachycentrus occidentalis, a filter-feeding caddisfly. Journal of the North American Benthological Society 9: 157-169.

Brown, WS 2005 Trichoptera of Gunnison County, Colorado, USA