Caddisflies: a caddisfly
(Trichoptera: Odontoceridae: Odontocerinae) Profile prepared by Sarah Foltz, The Xerces Society for Invertebrate Conservation
This vulnerable species is restricted to the Coastal and Cascade Ranges of Oregon and California, where it is known from small, cool, densely forested streams in old-growth or mature forest watersheds. Populations appear to be patchily distributed and exceedingly localized; fewer than 30 total locations are currently known and it is not abundant at any location. The loss of trees through timber harvest poses serious threats, since this species occupies mature forested habitats, and trees provide shade that maintains appropriate water levels and temperatures for larval and pupal development. Sedimentation, eutrophication, and chemical pollution could also impact this species, since Odontocerid larvae generally burrow under gravel, sand, or silt, and, like most caddisflies, have highly specific water quality requirements. Re-evaluation of this species’ status at the known sites (last surveyed between 1950 and 1999) is critical in identifying both its current distribution and its conservation needs.
Adult: A small, dull-colored moth-like insect. Adults in this family lack ocelli, and have antennae which are usually longer than the fore wings. The family is defined more precisely by wing venation (Wiggins 2004). Schmid (1968) provides a complete description for adults, including diagnostic characters for adult male and female, a photograph of the female, and figures of male and female wings, male genitalia (lateral, face view and aedeagus), and female genitalia (ventral) (Wisseman, pers. comm.). The species, originally described by Banks (1905), is the only species in the Namamyia genus.
Immature: The larvae of this species can be distinguished from other odontocerids by the heavily setate abdominal segment I (both dorsally and ventrally), and by the lack of ventral gills. The dorsum of the head is pebbled in texture and bears a ridge along each side. Larvae can reach up to 2 mm (0.08 in.) in length (Wiggins 1996). Larval cases in this family are made of large and small rock fragments held together by silken mortar joints, and are remarkably strong and resistant to crushing, The case of this species is curved and somewhat tapered, and up to 30 mm (1.2 in.) in length (Anderson 1976). It is coarser in texture than those of the closely related Nerophilus genus (Wiggins 1996). For additional descriptive information, see Wiggins (1996).
This species is restricted to the Coastal and Cascade Ranges of Oregon and California, occurring as far south as Kern Co., CA. In Oregon it is known from Benton, Curry, Jackson, Josephine, Lane, and Marion counties. Populations appear to be patchily distributed and exceedingly localized. Fewer than 30 total locations are currently known and it is not abundant at any location (Wisseman 2008, pers. comm.).
Forest Service/BLM Lands: Documented occurrences are from the Rogue River, Siskiyou, Siuslaw, and Willamette National Forests (Anderson 1976), including a recent (1999) occurrence in Siskiyou National Forest (Borgias and Wisseman 1999).
Inventory: Re-evaluation of this species’ status at the known sites (last surveyed between 1950 and 1999) is critical in identifying both its current distribution and its conservation needs. Abundance estimates for this species at new and known sites would also assist future conservation efforts, since population size is important in evaluating the stability of a species at a given locality. Small, cool, densely forested streams in old-growth or mature forest watersheds are good candidates for new population sites (Anderson 1976, Wiggins 1996, Wisseman 2008, pers. comm.).
Management: Protect all new and known sites and their associated watersheds from practices that would adversely affect any aspect of this species’ life cycle. Riparian habitat protection, including maintenance of water quality, substrate conditions, and canopy cover, would likely benefit and help maintain this species.
Anderson, N.H. 1976. The distribution and biology of the Oregon Trichoptera. Oregon Agricultural Experiment Station Technical Bulletin, 134:1-152.
Banks, N. 1905. Descriptions of new Nearctic neuropteroid insects. Transactions of the American. Entomological Society 32: 1-20.
Borgias, D. and Wisseman R.W. 1999. Report on the 1998 and 1999 survey for Rhyacophila colonus, in forested torrents near O’Brien, Oregon. The Nature Conservancy of Oregon. Prepared for Diane Perez, Siskiyou National Forest.
Field, C.B., Mortsch, L.D., Brklacich, M., Forbes, D.L., Kovacs, P., Patz, J.A., Running, S.W. and M.J. Scott. 2007. Chapter 14: North America. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Parry, M.L., Canziani, O.F., Palutikof, J.P., van der Linden, P.J. and Hanson, C.E., eds.). Cambridge University Press, Cambridge, UK. Available at: www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter14.pdf.
NatureServe. 2008. “Namamyia plutonis.” NatureServe Explorer: An online encyclopedia of life [web application]. Feb. 2008. Version 7.0. NatureServe, Arlington, Virginia. 21 Oct. 2008.
Schmid, F. 1968. Quelques Trichopteres nearctiques nouveaux ou peu connus. Naturaliste Canadien 95 (3): 673-98.
Wiggins, G.B. 1996. Larvae of the North American Caddisfly Genera. 2nd ed. University of Toronto Press, Toronto. 424pp.
Wiggins, G.B. 2004. Caddisflies: the underwater architects. University of Toronto Press, Toronto. 292pp.
Wisseman, R.W. 2008. Personal communication with Sarah Foltz.