This is not a forbidden free-living caddisfly but is an example of a caddisfly
The population size and trend of forbidden free-living caddisfly is unknown in Washington.
Caddisflies are aquatic insects. They are very sensitive to water quality and changes in water flow. Caddisflies in general are often considered an indicator of high-quality streams, suggesting that they are particularly vulnerable to changes in their habitat.
Description and Range
Physical description
Caddisflies are closely related to the Lepidoptera (moths and butterflies). The adult’s body and wings are covered with long silky hairs (setae) – a distinctive characteristic of the order. Caddisflies are aquatic in the immature stages.
Ecology and life history
This species is associated with cold springs and spring channels at mid- to high altitudes.
During the day, adults hide in cool, moist environments such as the vegetation along riverbanks. Few caddisfly adults have actually been observed feeding; they imbibe nectar.
Adults live several weeks and usually mate on vegetation or rocks surrounding water. Eggs, in masses numbering up to 800, are laid within a jelly that swells on contact with water. A female may wash off a partially extruded egg mass by dipping her abdomen into water during flight, or she may place the mass on stones in the water or on aquatic plants just above the water. Young larvae hatch within a few days and progress through multiple instars before emerging as a winged adult.
Although most larvae feed on aquatic plants, algae, diatoms, or plant debris, a few are predatory on other aquatic insects, crustaceans, and mollusks, and a few are omnivorous. The larvae play an important role in the aquatic community, reducing plant growth and disposing of animal and plant debris.
Caddisfly adults sometimes emerge in large numbers, often forming swarms. Adults tend to remain somewhat near the emergence site where oviposition occurs. They tend to disperse shorter distances in dense forest compared with more open vegetation. Although dispersal flights are common, such flights are relatively short and only occur immediately following emergence.
Geographic range
This species is uncommon in the high Cascades of Washington. It was recently reported from Mt. Rainier National Park, Lewis and Pierce Counties. It has also been reported in Clackamas County, Oregon, and British Columbia.
For a map of range-wide distribution and conservation status of this species, check out NatureServe Explorer.
Climate vulnerability
Sensitivity to climate change
High
Little information is available on this Rhyacophila vetina, an uncommon species of caddisfly reported in only a few high-elevation locations in the High Cascades region. Little is known about this species, but caddisflies in the genus Rhyacophila are fairly large and are free-living in their larval stage (i.e. they do not build cases until the pupae stage), making them particularly vulnerable to predation. All species in this genus are restricted to streams or rivers in the larval and pupae stages, and given that Rhyacophila vetina only occurs in high-elevation streams, it is likely tied to coldwater conditions as well. Climate sensitivity for this species is likely tied primarily to this specialized habitat, which is particularly vulnerable to warming air and water temperatures, low summer flows, sedimentation from upstream erosion, and habitat fragmentation from nearby human activity (i.e. forestry practices and road construction). Caddisflies in general are often considered an indicator of high-quality streams, suggesting that they are particularly vulnerable to changes in their habitat.
Exposure to climate change
Moderate-
High
- Increased air and water temperatures
- Low summer flows
- Increased sedimentation and erosion
Conservation
Conservation Threats and Actions Needed
- Resource information collection needs
- Threat: Lack of data on current status and distribution
- Action Needed: Determine distribution and population status
- Fish and wildlife habitat loss or degradation
- Threat: Water quality is of extreme importance to aquatic insects
- Action Needed: Protect riparian habitats
- Climate and severe weather
- Threat: Drying of streams
- Action Needed: Determine distribution and population status
See the Climate vulnerability section for more information about the threats posed by climate change to this species.
Resources
References
Anderson, N. H. 1976. The distribution and biology of the Oregon Trichoptera. Oregon Agricultural Experiment Station Technical Bulletin, 134:1-152.
NatureServe. 2014. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org.
Rasmussen, A.K., & Morse, J.C. 2021. Distributional Checklist of Nearctic Trichoptera (Fall 2021 Revision). Unpublished, Florida A&M University, Tallahassee. 519 pp.
Ruiter, D. E., B. C. Kondratieff, R. A. Lechleitner, and R. E. Zuellig. 2005. An annotated list of the caddisflies (Trichoptera) of Mount Rainier National Park, Washington, USA. Transactions of the American Entomological Society 131(1/2): 159-187.
Ruiter, D. E. 1995. The genus Limnephilus Leach (Trichoptera: Limnephilidae) of the New World. Ohio Biological Survey Bulletin, new series, 11: 1-200.
Wold, J. L. 1974. Systematics of the genus Rhyacophila (Trichoptera: Rhyacophilidae) in western North America with special reference to the immature stages. M.S. thesis, Oregon State Univ., Corvallis.
D. Ruiter, pers.comm.