Trichoptera: Hydroptilidae of Gunnison County, ColoradoHydroptila ajax
Microcaddisfly Ross 1938
Updated 28 January 2026
TSN 115643
Good Links
On this website:
Introduction to Hydroptilidae
Other Websites:
Photos, Map, Taxon Identifier Numbers - from the Global Biodiversity Information Facility Hydroptila ajax at GBIF
Photos, Map, Museum specimens, DNA - Barcodinglife.org
Photo - Mandibles from http://inverts.cmnh.org/Ent_Hydroptilid_morph.htm
References
Blinn,DW and Ruiter,DE 2006 Tolerance values of stream caddisflies (Trichoptera) in the lower Colorado river basin, USA. The Southwestern Naturalist 51(3):326-337.
Abstract: "One hundred and four caddisfly species within 42 genera and 17 families were collected from 93 stream sites in the xeric landscape of the lower Colorado River Basin, USA. Species richness showed a significant negative correlation with channel embeddedness. Forestland had higher species richness than grassland, desert, or urban caddisfly assemblages, and fewer caddisfly species occurred in the salt-cedar (Tamarix) than in willow-alder (Salix-Alnus) and cottonwood-sycamore (Populus-Plantanus) riparian communities. Hydroptilidae comprised nearly 35% of the average relative abundance of caddisflies and were generally tolerant of impaired stream environments. Hydroptila arctia composed the greatest relative proportion of species. Adjusted specific conductance and channel embeddedness metrics showed close agreement with published tolerance values for caddisfly species listed by the U.S. Environmental Protection Agency; genera were in less agreement. Amphicosmoecus canax, Brachycentrus americanus, Culoptila moselyi, Glossosoma ventrale, Ochrotrichia ildria, Psychoglypha schuhi, and Ylodes reuteri were most commonly associated with streams with low salinities and low embeddedness, whereas Cheumatopsyche enonis, Hydropsyche auricolor, Hydroptila ajax, Hydroptila arctia, Neotrichia okopa, Smicridea signata, and Smicridea fasciatella reached highest numeric importance in streams with high salinities and embeddedness."
Cobb, DG, Flannagan,JF 1990 Trichoptera and substrate stability in the Ochre River, Manitoba. Hydrobiologia, 206 (1)29 - 38. DOI 10.1007/BF00018967 PDF
Gerth,WJ; Murphy,CA and Arismendi,I 2023 Caddisfly dives for oviposition: Record-shattering depths and poor life choices in a dammed river system. Freshwater Science 42(1) 104-117.
Abstract: "Oviposition is a critical step in the life cycles of aquatic insects. Adult caddisflies exhibit a variety of oviposition methods. In some species, females enter freshwaters to oviposit on submerged substrates. Here, we compile information on North American caddisflies that are known to dive and swim to oviposit and have sexually dimorphic leg characteristics that may be adaptations for swimming, diving, or both. We also report unexpected underwater captures of adult females of 3 caddisfly species in Willamette Basin reservoirs in Oregon, USA, including the deepest dive depths ever recorded for adult female caddisflies. From these captures, we note sexually dimorphic leg widening in the species Hydropsyche centra Ross, for the first time, confirm widened mesothoracic leg segments of Hydropsyche occidentalis Banks, 1900 adult females, and note fringes of long hairs on meso- and metathoracic tibiae and basal tarsal segments of Hydroptila argosa Ross, females. We also note fringes of long hairs on the meso- and metathoracic legs of Hydroptila ajax Ross, females from the banks of the Willamette River. The presumed oviposition attempts of caddisflies underwater in large, deep reservoirs suggest that these caddisflies may misinterpret oviposition cues in altered habitats and waste reproductive efforts. Greater understanding of caddisfly oviposition methods and abilities may be important for long-term conservation and restoration efforts supporting biodiversity in freshwater habitats."
Herrmann,SJ; Ruiter,DE and Unzicker,JD 1986 Distribution and records of Colorado Trichoptera. Southwestern Naturalist 31(4), 421-457.
shows this species is present in Gunnison County
Keiper,JB 1998 Biology, larval feeding habits, and resource partitioning by microcaddisflies (Trichoptera: Hydroptilidae). PhD THesis Kent State University.
Ross, HH 1938 Descriptions of Nearctic Caddisflies. Bulletin of the Illinois Natural History Survey 21:101-183. PDF
Ruse,LP and Herrmann,SJ 2000 Plecoptera and Trichoptera species distribution related to environmental characteristics of the metal-polluted Arkansas River, Colorado. Western North American Naturalist 60 (1) 57-65. PDF
H. ajax was found at one site above and two sites below the Pueblo dam in the Arkansas river. Quote from page 62: "Although no stoneflies were collected downstream of Pueblo Reservoir, the hydropsychids Cheumatopsyche pettiti and Hydropsyche occidentalis and the hydroptilids Hydroptila ajax and Ochrotrichia stylata were dominant at AR19 and AR20. [downstream of the reservoir]"
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 73: "This species was collected from sites along the plains ranging from near the mountain plains interface east to North Platte, Nebraska." The elevation range is 2,850-5,400 feet and the adults emerge from June-September.
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