Bug Bites: Western Glacier Stonefly

Western Glacier Stonefly, Photo: USGS

Photo by USGS


The larvae of this stonefly live in mountain streams fed by icy water melting from glaciers. The glaciers are shrinking due to climate change.

Fun Facts:

  • • The western glacier stonefly is one of 7 species of globally rare insects within Glacier National Park, Montana.
  • • Stoneflies play a significant role in many aquatic ecosystems, decomposing leaves and other organic material thus forming the base of the food chain. Fly fishers have long recognized the important role stoneflies play in providing nutrients for fish.

Conservation Status:

The western glacial stonefly  (Zapada glacier) exists in small, scattered populations, known from only 5 small streams in Glacier National Park, Montana.  The species has very narrow habitat requirements, surviving in extremely cold glacial water.  The glaciers that feed streams the WGS requires for survival are disappearing rapidly due to climate change.


  • • Loss of caused by the disappearance of glaciers due to climate change.

Conservation Efforts:

The U.S. Fish and Wildlife Service is currently considering protections of western glacial stonefly populations under the Endangered Species Act.

To protect habitat, the reduction of greenhouse gas pollution is essential. This will slow global warming and ultimately stabilize the climate system, protecting the cold water habitat in Glacier National Park that Z. glacier depends upon.

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