Caddisflies: a caddisfly
Namamyia plutonis

(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.

Printable profile

conservation status
Global Status (2005): G3
Rounded Global Status: G3- Vulnerable
National Status (United States): N3
State Statuses: California: SNR, Oregon: S3 (Vulnerable in the state due to a restricted range, relatively few populations, recent and widespread declines, or other factors making it vulnerable to extirpation).
(NatureServe 2008).
identification

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).

life history
Most trichopterans in temperate latitudes are univoltine (Wiggins 1996), developing from the egg through five larval instars, pupating and emerging as adults within a single year. Larvae in this family have a burrowing life-style mwhich is accommodated by the unique architecture of their case. The diet of this species is unclear, but gut content analyses of other North American odontocerid genera reflect both predacious feeding (e.g. insect parts) and scavenging (e.g. detritus) (Wiggins 1996). Larvae of this species have been collected from May to September and the flight period of adults is from May to July (Anderson 1976).
distribution

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).

habitat associations
This species is known from small, cool, densely forested streams in old-growth or mature forest watersheds (Wisseman pers. comm., Wiggins 1996). Odontocerid larvae generally burrow under gravel, sand, or silt (Wiggins 1996); this species has been found in core samples taken from areas of coarse gravel intermixed with silt and organic sediments (Anderson 1976).
threats
Most trichopteran species have highly specific preferences with regard to water temperature, velocity, dissolved-oxygen levels, and substrate characteristics, and are therefore sensitive to a wide array of habitat alterations. 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. Continued global climate change may further threaten this species. Projected changes due to this phenomenon include increased frequency and severity of seasonal droughts and flooding, reduced snowpack to feed river flow, increased siltation, and increased air and water temperatures (Field et al. 2007), all of which could unfavorably impact this species’ habitat and long-term survival. Sedimentation, eutrophication, and chemical pollution caused by development and road construction could also impact this species.
conservation needs

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.

references

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.

The Xerces Society • 628 NE Broadway Ste 200, Portland OR 97232 USA • tel 855.232.6639 • fax 503.233.6794 • info@xerces.org
site mapcontactgivecontact the webmaster