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Trichoptera: Limnephilidae of Gunnison County, Colorado

Dicosmoecus atripes
Silver stripe caddis, Giant Caddisfly, October Caddis, Fall Caddis, Halloween Caddis, Great Orange Caddis, Giant Orange Sedge

(Hagen) 1875

Updated 26 Aug 2020
TSN 116266

Good Links

On this website:
Limnephilidae Introduction

Other Websites:
Fishing the October Caddis Hatch on the Yakima River of Washington http://www.worleybuggerflyco.com/insectidentifa/october_caddis.htm

Illustration - University of Alberta Entomology Collection Species page
     Has habitat, range and more.

Photos, Map, Museum specimens, DNA - Barcodinglife.org


Banks, N. 1943 Notes and descriptions of Nearctic Trichoptera. Bulletin of the Museum of Comparative Zoology at Harvard College 92: 341-369, plates 1-6.

Dodds,GS and Hisaw,FL 1925 Ecological studies on aquatic insects. III. Adaptations of caddisfly larvae to swift streams. Ecology 6(2)123-137. Abstract and first page

Goodrich,AL, Jr. 1935 The thoracic sclerites of a Trichopterous pupa, Dicosmoecus atripes Hagen. (Limnophilidae) Transactions of the American Microscopical Society 54(1): 57-64. Abstract

Goodrich,AL, Jr. 1937 The head capsule of a Trichopterous pupa, Dicosmoecus atripes Hagen (Limnophilidae). Transactions of the American Microscopical Society 56(2) 243-248.

Goodrich,AL, Jr. 1941. The external anatomy of the pupal abdomen in Dicosmoecus atripes Hagen (Trichoptera, Limnephilidae). Journal of the Kansas Entomological Society 14:134-143.

Gotceitas, V 1985 Formation of aggregations by overwintering fifth instar Dicosmoecus atripes larvae (Trichoptera). Oikos 44(2) 313-318.
     Abstract: " In laboratory experiments fifth instar Dicosmoecus atripes (Hagen) larvae formed aggregations under uniform environmental conditions, variations in which (e.g. current, substrate, etc.) could function in bringing larvae together to a 'suitable' site of attachment in the field. In selecting an attachment site, larvae selected substrates with attached conspecifics already present over substrates without attached conspecifics. Given the choice between an attachment site with empty conspecific larval cases attached or glass shell-vials similarly attached, D. atripes larvae chose the site with conspecific larval cases. It appears that D. atripes larvae are capable of tactile or visual recognition of conspecifics, and use their presence as cues in attachment site selection. There was no experimental evidence of chemical cues between larvae in aggregation formation. "

Gotceitas,V and Clifford,HF 1983 The life history of Dicosmoecus atripes (Hagen) (Limnephilidae: Trichoptera) in a Rocky Mountain stream of Alberta, Canada. Canadian Journal of Zoology 61(3)586-596.
     Abstract: " Dicosmoecus atripes (Hagen) has a 2-year life cycle in Dyson Creek, Alberta, a second order foothills stream of the eastern Canadian Rockies. Emergence and oviposition occur from August to mid-October. The first winter is spent as first instar larvae, the second as inactive fifth (final) instars in a form of diapause. No growth was observed in overwintering first instar larvae, and a significant (P < 0.05) weight loss was recorded in overwintering fifth instar larvae. Temperature seems to be the most important factor responsible for the 2-year life cycle. Annual production was estimated at 91.4 mg*m2*year-1, with an annual production and biomass turnover (P/B) ratio of 4.97. Larval diet and microhabitat changed between instars. The proportion of diatoms in the diet of early instar larvae was significantly (P <0.001) greater than that of third and later instars. Early instar larvae inhabit stream margins, while larvae of third and later instars were mainly found in midstream reaches. Larvae of all instars preferred pools to riffles. Abiotic factors important in microhabitat selection seemed to differ between larval instars."

Hagen HA. 1874 Report on the Pseudo-Neuroptera and Neuroptera collected by Lieut. W. L. Carpenter in 1873 in Colorado. Pages 571-606 in Hayden FV, Annual Report of the United States Geological and Geographical Survey of the Territories, Embracing Colorado, Being a Report of Progress of the Exploration for the Year 1873 7:571-606.
     Described as Platyphylax atripes.

Herrmann,SJ; Ruiter,DE and Unzicker,JD 1986 Distribution and records of Colorado Trichoptera. Southwestern Naturalist 31 4, 421-457.
     The authors show this species present in Gunnison County.

Holzenthal,RW; Blahnik,RJ; Prather,AL and Kjer,KM 2007 Order Trichoptera Kirby, 1813 (Insecta), Caddisflies. Zootaxa, 1668: 639-698. PDF
      Illustration of Dicosmoescus sp. case on page 655 that looks similar to their cases in the Elk Mountains.

Lessard,JL; Merritt,RW and Cummins,KW 2003 Spring growth of caddisflies (Limnephilidae: Trichoptera) in response to marine-derived nutrients and food type in a Southeast Alaskan stream. International Journal of Limnology 39(1) 3 - 14. PDF
     Abstract: "The short-term stimulation of production, due to marine-derived nutrients (MDN) from spawning salmon, is well documented for certain trophic levels in stream communities (e.g., algae and insect biomass). The effect of these nutrients on the stream ecosystem as a whole, however, remains unclear especially later in the year. Trichopterans have been shown to feed on salmon and other fish carcasses and there is evidence for greater growth rates in the presence of salmon tissue. To address the question of long-term MDN subsidy on trichopterans, we investigated the growth of three limnephilid caddisflies in the spring in the Harris River on Prince of Wales Island, Southeast Alaska. The Harris River has a natural waterfall barrier to salmon and receives large runs of pink (O. gorbuscha) and chum (O. keta) salmon each fall. We selected two shredding caddisflies (Onocosmoecus unicolor) and (Psychoglypha spp.) and one facultative scraper, (Dicosmoecus atripes) for our study. We had two objectives : 1) compare the spring growth of larval caddisflies in a stream section that receives a large autumn run of salmon with their growth in a stream section that is blocked from receiving salmon (due to an impassable waterfall), and 2) compare the growth of shredders with that of a facultative scraper when provided either leaves or biofilm on rocks as food.
Insects were placed in growth boxes in May 2001 with either conditioned alder leaves or stream rocks as food sources. The boxes were placed along with temperature loggers in both the salmon (below the waterfall) and non-salmon (above the waterfall) reaches. The boxes were removed 40 days later. In-stream samples were taken of each caddisfly initially and at the end of the experiment to establish in-stream growth versus growth in the boxes. All larvae were coaxed from their cases, measured for total wet length, dried and weighed. Only D. atripes and Psychoglypha spp. were growing during our experiment and both showed very high relative growth rates in the Harris River. Psychoglypha spp. and O. unicolor were both significantly larger in the leaf boxes and D. atripes was significantly larger in the rock boxes. Both D. atripes and Psychoglypha spp. had significantly greater relative growth rates between food types (on biofilm on rocks and leaves respectively). These results support the notion that D. atripes are most likely facultative scrapers at least in their first year of growth. None of these caddisflies showed differences in their final mean weights or relative growth rates between stream sections, suggesting no effect of MDN on their spring growth in the Harris River. Further research on caddisfly communities in the fall and winter will help clarify if MDN has an influence on the abundance and life history of these species closer to the salmon run. This study questions the long-term influence of MDN on stream communities, particularly those populations that do most of their production in the spring, months after salmon carcasses are no longer visible."

Luedtke,RJ and Brusven,MA 1976 Effects of sand sedimentation on colonization of stream insects. Journal of the Fisheries Board of Canada, 33(9), pp.1881-1886. PDF
     Abstract: " Driftnets, basket samplers, and artificial streams were used to investigate the influence of heavy sand accumulations on insect drift, colonization, and upstream movements in Emerald Creek, northern Idaho. Most riffle insects successfully passed through low-velocity, sandy reaches 80 m long. Upstream movements on sand were impeded by flows as low as 12 cm/s, except for the heavily cased caddisfly Dicosmoecus sp."

Mihuc,TB; Mihuc,JR 1995 Trophic ecology of five shredders in a Rocky Mountain stream. Journal of Freshwater Ecology 10 (3) 209-216. PDF
     Abstract: " The trophic ecology of five shredder taxa found in Mink Creek, Idaho was determined in laboratory food quality experiments to assess the obligate or facultative nature of resource utilization among lotic taxa commonly referred to as detritivores. The experiments tested resource assimilation for each taxon among three major resources available to primary consumers in streams; periphyton, fine particulate detrital material (FPM) and coarse particulate detrital material (CPM). Growth of each taxon was determined on each resource in laboratory experiments conducted at 10° C.
Growth results indicate that only one of the five taxa (middle-late instar Dicosmoecus atripes) was an obligate CPM detritivore. The remaining four taxa (Amphinemura banksi, Lepidostoma sp., Podmosta delicatula, and Zapada cinctipes) were generalists capable of growth on at least two of the three resource types. All four generalists exhibited growth on periphyton and CPM resources suggesting that these taxa can utilize both autochthonous and allochthonous resources. Our results do not support the idea that taxa with similar mouthpart morphology, specifically shredders, exhibit similar trophic relationships."

Resh,VH; Hannaford,M; Jackson,JK; Lamberti,GA and Mendez,PK 2011 The biology of the limnephilid caddisfly Dicosmoecus gilvipes (Hagen) in Northern California and Oregon (USA) Streams. Zoosymposia, 5(1)413-419. PDF
     This is about a different species yet it may shed some light on the life history of our local Dicosmoecus.
Abstract: "The limnephilid caddisfly Dicosmoecus gilvipies (Hagen) occurs in many streams of northwestern United States and British Columbia. Because of the large size of the fully grown larva, its synchronous emergence pattern, and its frequent imitation by fly-fishing anglers, D. gilvipes is one of the best known North American aquatic insects. Egg masses are found at the bases of Carex sedges. Cases of early larval instars are made of organic material and detritus; 3rd and 4th instars incorporate pebbles into cases. The 5th-instar case is made entirely of mineral material. Larvae can travel up to 25 m per day, and are predominantly scraper-grazers. Fifth instars attach their cases to the underside of boulders in mid-summer and remain dormant until pupation in autumn. All northern California populations known are univoltine. Adult females use sex pheromones to attract males; most males come to trapped females in the 1st hour after sunset. In laboratory studies, males and females fly during the mate attraction period but generally not at other times. Males but not females exhibit circadian rhythms that govern flight periodicity. In enclosures to study biotic interactions, the density of D. gilvipes larvae has a negative effect on the densities of sessile grazers. This species has been widely used in trophic and behavioral studies conducted in the laboratory and field, and may be a model organism for ecological studies of caddisflies and other benthic macroinvertebrates."

Wiggins,GB, and Richardson,JS 1982 Revision and synopsis of the caddisfly genus Dicosmoecus (Trichoptera: Limnephilidae: Dicosmoecinae). Aquatic Insects 4:181-217.
     Abstract: "Six species of Dicosmoecus are recognized: the palatus species group of Siberia and Japan [palatus (McL.), obscuripennis Banks, and jozankeanus Mats.)]; and the atripes species group of western montane North America [atripes (Hagen), gilvipes (Hagen), and pallicornis Banks]. D. obscuripennis is re-established as a valid species distinct from palalus and recorded from the Yukon Territory and Alaska, and also Siberia. Keys are provided for identification of males, females, and larvae. Hypotheses of phylogeny and biogeography are proposed, stating that the palatus and atripes species groups evolved independently in Asia and North America respectively; and that obscuripennis of the palatus group extended its range to North America during the Pleistocene Beringian land connection between the two continents.
Data on food, life cycle, habitat, and distribution are given for the North American species. Most Dicosmoecus appear to be generalized predator-shredders with robust, toothed mandibles; but fifth instar larvae of D. gilvipes feed mainly by scraping rocks for diatoms, a behaviour which is evidently responsible for eroding the slender blade and weakly formed teeth of the mandible, unique to this species, to a uniform scraping edge. D. gilvipes is further distinctive in usually having a 1-year life cycle, whereas atripes and the other North American species usually have a life cycle of 2 years. "

Wiggins,GB, and Richardson,JS 1989 Biosystematics of Eocosmoecus, a new Nearctic caddisfly genus (Trichoptera: Limnephilidae, Dicosmoecinae) Journal of the North American Benthologicavl Society, 8(4) 355-369. Abstract and first page
     Quote from abstract: "Keys distinguishing Eocosmoecus, Onocosmoecus, and Dicosmoecus are given for adults, pupae, and larvae. "

Wisseman,RW 1987 Biology and distribution of the Dicosmoecinae (Trichoptera: Limnephilidae) in western North America. MS thesis Oregon State University PDF
     Abstract: "Literature and museum records have been reviewed to provide a summary on the distribution, habitat associations and biology of six western North American Dicosmoecinae genera and the single eastern North American genus, Ironoquia. Results of this survey are presented and discussed for Allocosmoecus, Amphicosmoecus and Ecclisomyia. Field studies were conducted in western Oregon on the life-histories of four species, Dicosmoecus atripes, D. gilvipes, Onocosmoecus unicolor and Ecclisocosmoecus scylla. Although there are similarities between genera in the general habitat requirements, the differences or variability is such that we cannot generalize to a "typical" dicosmoecine life-history strategy. A common thread for the subfamily is the association with cool, montane streams. However, within this stream category habitat associations range from semi-aquatic, through first-order specialists, to river inhabitants. In feeding habits most species are omnivorous, but they range from being primarily detritivorous to algal grazers. The seasonal occurrence of the various life stages and voltinism patterns are also variable. Larvae show inter- and intraspecific segregation in the utilization of food resources and microhabitats in streams. Larval life-history patterns appear to be closely linked to seasonal regimes in stream discharge. A functional role for the various types of case architecture seen between and within species is examined. Manipulation of case architecture appears to enable efficient utilization of a changing seasonal pattern of microhabitats and food resources."

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