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Montana Field Guide

Montana Field Guides

A Rhyacophilan Caddisfly - Rhyacophila donaldi

Native Species

Global Rank: G2G3
State Rank: SNR

Agency Status


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General Description
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Species Range
Montana Range


Range Comments
Described from Alberta in the subalpine area of Waterton National Park (6000 feet) (Nimmo, 1977) and recently reported from Glacier National Park, Montana (Giersch and Hauer, 1999).

R. donaldi is restricted to the northern Rocky Mountains, where it lives in cold alpine/subalpine streams fed by permanent snowmelt, glaciers or icefields. Giersch and Hauer (1999) reported this species from small, turbulent glacier creeks to tiny alpine trickles. Along with R. glaciera Denning, this species occurs in the highest, coldest streams in Glacier National Park. These caddisfly larvae are free-living forms that move actively searching for food (predatory) with no case, until just before pupation. The trophic relationships of larvae of Rhyachophila are predatory on other insects, especially chironomid midges and simulidae (blackfly larvae) (Merritt and Cummins 1996).

Food Habits
Most Rhyacophila species are predators feeding mostly on aquatic insects, especially midges and blackflies

R. donaldi is a regional endemic only known to occur in high alpine snowmelt and spring fed streams along the Rocky Mountain Cordillera in Glacier National Park of Montana, Waterton, Banff and Jasper National Parks of Alberta & British Columbia. With the increased evidence of global warming, this species could be considered a candidate for the USFWS T&E species list.

Threats or Limiting Factors
Specific threats to Montana populations of R. donaldi would include global warming and the melting of glaciers. If the existing glaciers disappear from Glacier National Park, as predicted in 25 years (2030-2040) this species will likely be extirpated from the state and possibly extinct. In general, cold-stenothermic (cold-water specialists) invertebrate populations are affected by changes to aquatic habitat, such as alteration of flow patterns, streambed substrate, thermal characteristics, and water quality.

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Citation for data on this website:
A Rhyacophilan Caddisfly — Rhyacophila donaldi.  Montana Field Guide.  .  Retrieved on , from