Trichoptera: Brachycentridae of Gunnison County, ColoradoBrachycentrus americanus
Log Cabin Casemakers, American grannom (Banks) 1899
Updated 11 Feb 2010
TSN 116912
Description
These are stream and river insects. Larvae live in a tapered, four-sided (square) wooden case with a "log cabin" or transverse arrangement of twigs, pine needles and anything else useful in their habitat. Easily identifiable in the field or lab due to the distinctive case. The larvae are bright green when alive. The larvae fasten the front edge of their case to the substrate with silk and raise their second and third pair of legs in the current to filter food particles out of the water column.
Locations Collected
Common and widespread in this county, state and country as well as the entire nearctic and eastern palearctic. The Illinois Natural History Survey (INHS) Database shows this species is present "at Parlin", "South of Gunnison, near Cochetopa" and "the 1st bridge above Cow Creek Confluence". I have collected this species in Cement Creek, Coal Creek, East River near Crested Butte South, Slate River, Taylor River and the Gunnison River. While present in the upper East River Valley, it is less common.
Links
On this website:
Brachycentrus occidentalis
Outside Links:
Photos, Map, Museum specimens - Barcodinglife.org
Illustration - University of Alberta Entomology Collection Species page
Has illustration of male genitalia, description, habitat information, range and more.
PAN Pesticides Database http://www.pesticideinfo.org/List_AquireAll.jsp?Species=36&Effect=
References
Allan,JD 1987 Macroinvertebrate drift in a Rocky Mountain stream. Hydrobiologia 144, 261-268.
Working in Cement Creek in Gunnison County, Allan looked at aquatic insects drifting in the water column for 24 hour time periods during the summers of 1976 and 1977. On page 263, he briefly says "Trichoptera (mostly several species of Rhyacophila, but occasional Hydropsychidae and Brachycentrus americanus (Banks) always exhibited very low drift densities."
Banks, N. 1899. Descriptions of new North American neuropteroid insects. Transactions of the American Entomological Society 25:199-218.
Originally described as Oligoplectrum americanum.
Canton,SP; 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.
B. americanus relative abundance did not change above and below the mine.
Clements,WH; Carlisle,DN; Lazorchak,JM; Johnson,PC 2000 Heavy metals structure benthic communities in Colorado mountain streams. Ecological Applications 10(2)626-638. Abstract
Quote from page 633: "Rhyacophila sp.(Fig.5j) was the only caddisfly that showed a significant response to metal level and was lower at medium-metal sites. Differences among metal categories in abundance of the three other dominant caddisflies, (Brachycentrus americanus, Hydropsyche sp., and Lepidostoma sp.) and the blackfly Simulium sp. were not significant (Fig. 5g, h, i, k)."
Clubb,RW; Gaufin,AR; Lords,JL 1975 Acute cadmium toxicity studies upon nine species of aquatic insects. Environmental Research 9, 332-341.
Colburn,T (1982a) Aquatic insects as measures of trace element presence in water: Cadmium and Molybdenum. Aquatic Toxicology and Hazard Assessment: Fifth Conference, ASTM STP 766, J.G. Pearson, R.B. Foster, and W.E. Bishop, Eds., American Society for Testing and Materials, pgs 316-325.
She discusses a taxa from Coal Creek called Brachycentrus brachycentrus. There are two species of Brachycentridae in Coal Creek, Brachycentrus americanus and Micrasema bactro. I assume she was working with B. americanus since it is in the right genus, is more common and bigger than Micrasema. She collected insects from what she thought was a reference or clean site up Coal Creek, however it was below Elk Creek. Elk Creek has a rather nasty mine called the Standard Mine up near the headwaters, this mine is now a Superfund site. So her bugs may have had some metal exposure before the experiment. Anyway, she found that both live and dead insects bioaccumulated Cadmium and Molybdenum after only a few days in the Slate River. Levels of both metals increased over time in the insects. Interestingly the water samples showed no Molybdenum present, indicating the insects were accumulating Molybdenum from the sediments or pulses of Mo in the water at times other than the water samples were taken.
Denning, D. G. 1983 New and interesting Trichoptera from the western United States. Pan-Pacific Entomologist 58, 206-215.
Compares the adults of B. americanus and Brachycentrus occidentalis among other things.
Flint, O. S., 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.
Has keys to adult males.
Gallepp, G. W., Jr. 1975 The behavioral ecology of larval caddisflies, Brachycentrus americanus and Brachycentrus occidentalis. Dissertation Abstracts International 35: 4532.
Gallepp,GW 1974 Diel periodicity in the behavior of the caddisfly, Brachycentrus americanus (Banks). Freshwater Biology 4, 193-204.
Studied in an artificial stream and Lawrence creek in Wisconsin, B. americanus had a univoltine life cycle (one generation per year). Eggs were laid from mid June all summer. Larvae grew slower in the fall and winter, but faster in the spring. They pupated from May on and adults were present from June to September. B. americanus had 5 larvae instars with 2 sizes (sexual dimorphism) in the final instar. Females pupated in longer cases. Gallepp notes that B. americanus is usually an omnivorous, "sessile filter feeder". They attach the front of their case to the substrate and sit with their long middle and hind legs over their head in the current filtering food from the current with the bristles and spines on their legs. They tended to release large particles such as leaves, but brought smaller particles down to their mouth. Small objects were eaten with the shorter front legs (proleg) only. Other pieces of food were handled with all legs as needed.
Gallepp,GW 1977 Responses of caddisfly larvae (Brachycentrus spp.) to temperature, food availability and current velocity. American Midland Naturalist 98(1)59-84. Abstract
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.
Working in the Flathead River of Montana, the authors found that B. americanus larvae hatched from eggs in the fall and overwintered as early instar larvae. They grew rapidly as water temperatures rose in the spring, but temporarily halted growth during spring runoff. B. americanus emerged as adults during August and September. They avoided competition with Brachycentrus occidentalis larvae by slightly staggered life cycles, with adults of B. occidentalis emerging after peak runoff in late June.
Hauer,FR; Stanford,JA; Ward,JV 1989 Serial discontinuities in a Rocky Mountain river. II. Distribution and abundance of Trichoptera. Regulated Rivers: Research and Management 3, 177-182.
Herrmann,SJ; Ruiter,DE; 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 1606 to 3048m and adult collection dates are 17 April to 6 September.
Quote from page 425: "Denning (1983) compared the male and female of this species with B. occidentalis Banks 1911 making future incorrect identifications of the two adults unlikely. Flint (1984) wrote keys to adult males and larvae for the species of Brachycentrus in North America. " They list this species as present in Gunnison county.
Johnson,KR; Jepson,PC; Jenkins,JJ 2008 Esfenvalerate-induced case-abandonment in the larvae of the caddisfly (Brachycentrus americanus) Environmental Toxicology and Chemistry 27(2) 397–403. Abstract
Kohler,SL and Hoiland,WK 2001 Population regulation in an aquatic insect: the role of disease
Ecology 82(8) 2294-2305. Abstract and first page
Mecom, John O. 1972a Feeding habits of Trichoptera in a mountain stream. Oikos 23: 401-407. Abstract and first page
Mecom, John O. 1972b Productivity and distribution of Trichoptera larvae in a Colorado mountain stream. Hydrobiologia 40(2): 151 - 176. ISSN: 0018-8158 (Paper) 1573-5117 (Online) DOI: 10.1007/BF00016789 Abstract
Mecom, J.O. and K.W. Cummins. 1964 A preliminary study of the trophic relationships of the larvae of Brachycentrus americanus (Banks) (Trichoptera: Brachycentridae). Transactions of the American Microscopical Society 83: 233-243.
Palmquist K, Jepson P, Jenkins J 2008 Impact of aquatic insect life stage and emergence strategy on sensitivity to esfenvalerate exposure. Environmental Toxicology and Chemistry 27(8)1728-1734 Abstract
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; Poff,NL; 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
Ward,JV; Kondratieff,BC; Zuellig,RE 2002 An Illustrated Guide to the Mountain Stream Insects of Colorado. 2nd ed. University Press of Colorado, Boulder, Colorado. 219 pages.
Has an illustration of B. americanus and its classic case on page 118
Wiggins, GB 1996 Larvae of the North American Caddisfly Genera (Trichoptera). 2nd Edition. University of Toronto Press, 457 pages.
Has illustrations of the larvae and 4-sided case of B. americanus.
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