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Trichoptera: Glossosmatidae of Gunnison County, Colorado

Glossosoma verdonum (verdona)
Saddle Case Makers

Ross 1938
Updated 2 March 2022
TSN 117221


Although most sources have historically used the name Glossosoma verdona, this species is now called Glossosoma verdonum.

Good Links

On this website:
Glossosoma Introduction

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


Duffield,RM; Flint,OS and Nelson,CH 1994 Glossosoma verdona (Glossosomatidae: Trichoptera) in the diet of Brook Trout (Salvelinus fontinalis) in Libby Creek, Wyoming, USA. Journal of the Kansas Entomological Society 67(3) 277-282.
     Abstract: "Dietary samples from brook trout, Salvelinus fontinalis Mitchell, were analyzed to obtain information on the life history of the caddisfly, Glossosoma verdona Ross. The 220 samples that were obtained from brook trout from mid-May through mid-August contained 14,220 dietary items. Of these, 44 samples contained a total of 541 pharate, teneral, and mature adults of Glossosoma verdona. Analysis of the samples indicates that brook trout feed on G. verdona at a minimum of two periods in its life history, emergence and oviposition. The former occurs at a peak period during mid-June, whereas the latter occurs from late June to mid-July. The absence of G. verdona larvae in the diet of the brook trout is attributed to the absence of this stage in the stream during the sampling period. "

Irons,JG III 1988 Life history patterns and trophic ecology of Trichoptera in two Alaskan (U.S.A.) subarctic streams. Canadian Journal of Zoology, 66:1258-1265. Abstract

Poff,NL and Ward,JV 1988 Use of occupied Glossosoma verdona (Trichoptera: Glossosomatidae) cases by early instars of Baetis spp.(Ephemeroptera: Baetidae) in a Rocky Mountain stream. Entomological news (USA).

Poff,NL; Wellnitz,TA and Monroe,JB 2003 Redundancy among three herbivorous insects across an experimental current velocity gradient. Oecologia 134:262-269. PDF
     Abstract: "We conducted streamside experiments to determine if the ability of herbivorous insects to remove algal periphyton varies with local current velocity. We used two mayfly species (Baetis bicaudatus and Drunella grandis) and one caddisfly species (Glossosoma verdona), which differ from one another in body morphology and mobility. Periphyton was grown for 30 days on ceramic tiles in constant velocity to create similar initial forage conditions for grazers. Tiles were transferred to three velocity regimes characteristic of the natural streambed: slow (3-5 cm s-1), medium (15-20 cm s-1) and fast (32-41 cm s-1). Four grazer treatments (Baetis, Drunella, and Glossosoma alone, and all species combined) were repeated for each velocity treatment to isolate the effect of local current on grazer ability to crop periphyton. Grazers differed in their abilities to remove periphyton across current treatments. Glossosoma removed significantly (P<0.05) more periphyton at fast versus either slow or medium velocities; Baetis showed a similar (but non-significant) trend; and, Drunella always removed about 75% of periphyton, irrespective of current. At fast current, periphyton removal was equivalent among the species. At medium current, Drunella removed significantly more than both Baetis and Glossosoma, whereas at slow current, Drunella removed more than Baetis, which removed more than Glossosoma. Periphyton removal under the combined three-grazer treatment was similar qualitatively to the combined effects of individual grazers. More periphyton tended to be removed as current increased, with the fast versus slow contrast showing marginal significance (P=0.10). Under all current regimes, the quantity of periphyton removed did not differ from the null model expectation of simple additive effects among individual grazers (i.e., no facilitation or inhibition). These experiments show that for some species, herbivory varies with current, which suggests that the herbivore "function" of cropping periphyton may vary with the environmental context of local current. Under some local velocities, however, different herbivore species "function" similarly and are potentially redundant with respect to periphytic removal. In naturally heterogeneous streams characterized by sharp gradients in local current velocity, we expect current-dependent species interactions to be common and at least partially contribute to intra-guild co-existence of species."

Ross, HH 1938 Descriptions of Nearctic Caddisflies. Bulletin of the Illinois Natural History Survey 21:101-183.
     Describes this species on page 110-111 and in figure 15.

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: " During studies on filter-feeding and grazing caddisflies in the regulated upper Colorado River, a problem developed with the deep-release mechanism of Granby Dam and water had to be released from the surface for 16 days in August 1986. Maximum water temperatures exceeded the normal summer maxima by at least 4-5 C for up to 12 km below the reservoir. Samples taken along the longitudinal profile below the reservoir showed that populations of several caddisflies species, which had been numerically abundant in previous years, were virtually eliminated after this period of increased water temperature. Some species experienced immediate reductions, presumably due to larval/pupal mortality (e.g., Brachycentrus americanus, Glossosoma ventrale, G. parvulum), while others exhibited lagged responses over the next several months, presumably due to reduced hatching success and extensive winter mortality (e.g., Glossosoma verdona). Interestingly, at some sites, B. americanus and other caddisfly species were largely unaffected by the elevated temperatures. Species showing the greatest resilience to the thermal disturbance were either those having abundant terrestrial adults present at the time (e.g., Agapetus boulderensis) or those potentially having broad thermal tolerances (e.g., Brachycentrus occidentalis). Most studies concerning the effects of extreme temperature change on lotic organisms have dealt with heated effluents or the general thermal impacts induced by river regulation. This is the first report, that we are aware of, detailing the potential effect of short-term elevated temperatures on lotic macroinvertebrates in a river regulated by a deep-release dani."

Wellnitz,T and Poff,NL 2012 Current-mediated periphytic structure modifies grazer interactions and algal removal. Aquatic Ecology, 46(4) 521-530. PDF
     Abstract "By shaping the architecture and taxonomic composition of periphyton, stream current may create periphytic mats on which some grazers can feed and forage more effectively than others. Current-mediated periphytic structure also has the potential to foster positive interactions among grazers if one grazer's foraging facilitates another's access to algal food. To examine the extent to which these indirect effects of current influenced periphytic removal and grazer interactions, we conducted a mesocosm experiment with two common grazers, the caddisfly (Trichoptera) Glossosoma verdona and the mayfly (Ephemeroptera) Drunella grandis. Periphyton was allowed to colonize ungrazed tiles for 30 d and assume its natural growth form under three ranges of near-bed current, "slow" (1-5 cm s-1), "medium" (15-20 cm s-1), and "fast" (30-40 cm s-1). Tiles were then exposed to the two grazer species at five densities. A streambed survey quantified Glossosoma and Drunella distributions in relation to near-bed current and periphytic structure (i.e., diatom films vs. filamentous mats) in the Colorado River. After 22 days of grazing, periphytic removal by Glossosoma was influenced by near-bed current and attendant periphytic structure. In slow current, where senescent Ulothrix filaments were abundant, increased Glossosoma density was correlated with an increase in periphyton biomass. Larvae became entangled and immobilized by the diffuse and senescent Ulothrix mat that characterized slow velocity, and Glossosoma mortality and weight loss was greatest in this treatment. By contrast, Drunella reduced periphyton across all density and current treatments. Drunella density correlated with increased Glossosoma survivorship and weight gain in slow current. The driving mechanism for this facilitation appeared to be removal of entangling overstory filaments by Drunella. The streambed survey showed that Glossosoma were negatively associated with filamentous mats, lending support to the hypothesis that clearing action by Drunella in the slow current/senescent Ulothrix treatment facilitated Glossosoma growth and survival. Our study helps underscore the importance of evaluating species interactions over ranges of abiotic conditions and consumer pressure to understand the patterns and processes shaping benthic communities."

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
     The authors found Glossosoma verdonum at elevations from 6,650-10,850ft, adults were found from May-August.

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