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UW Researchers’ Discovery May Keep Insect off of Endangered Species List

November 17, 2017
close up photo of a long-bodied flying insect
This Zapada western glacier stonefly, once thought to only exist in Glacier National Park, has been found in Grand Teton National Park the last three summers by Lusha Tronstad, an invertebrate zoologist with the Wyoming Natural Diversity Database (WYNDD) at UW, and her research colleagues. The discovery has reopened the comment period by the U.S. Fish and Wildlife Service to determine whether the stonefly should be placed on the endangered species list. (Joe Giersch Photo)

The recent discovery of a rare aquatic insect in Grand Teton National Park by University of Wyoming researchers may keep it off the endangered species list.

Lusha Tronstad, an invertebrate zoologist with the Wyoming Natural Diversity Database (WYNDD) at UW, and colleagues have been finding Zapada glacier or western glacier stoneflies in the Tetons the last three summers.

“The stonefly was previously only known from northwestern Montana, but we heard a report a few years ago it may live in the Tetons,” Tronstad says. “We sampled in the Teton Range and found the stonefly in several alpine streams. Information from our study informed the U.S. Fish and Wildlife Service, and (the agency) reopened the comment period to reconsider the listing of this stonefly.”

According to a New York Times article earlier this month, the western glacier stonefly and another species, the meltwater lednian stonefly, were proposed, in October 2016, for protection under the Endangered Species Act. A year later, a final decision was expected.

However, the latest discovery of the western glacier stonefly in Grand Teton National Park and Montana’s Absaroka-Beartooth Wilderness has put that decision on hold.

“The reason they (U.S. Fish and Wildlife Service) put it out for comment again is because stoneflies were found 500 miles from where they were previously known in Glacier,” Tronstad says.

Stoneflies have long antennae, chewing mouthparts and two pairs of membranous wings. The insect ranges in size from one-quarter inch to 2.5 inches. Species are gray, black or brown.

woman sitting on the ground writing with mountains in the background
Lusha Tronstad takes notes after sampling a rock glacier-fed stream in the Teton Mountains. Tronstad has spent the last three summers documenting western glacier stoneflies in the Tetons. (Scott Hotaling Photo)

“These insects are really special, in that they live in streams that are near glaciers,” Tronstad says. “The reason people care is because the glaciers are melting. Glaciers, which are crucial to the stoneflies’ habitat, will be lost.”

Oliver Wilmot, an invertebrate zoologist with the WYNDD, concurs.

“The habitat they are in is receding. Their very specific habitat is disappearing,” Wilmot says.

As these cold mountain streams that abut glaciers disappear due to a warming climate, the stonefly will not be able to retreat to alpine stream habitats at higher altitudes, he says.

Stoneflies are important biological indicators of water quality. Stoneflies are considered “shredders,” meaning they break down leaves -- that fill the glacier streams -- into smaller pieces.

“Think about your yard if you never raked it. They (stoneflies) consume leaves in streams and are important for the carbon cycle,” Tronstad says.

Wilmot estimates that, after sampling 15 streams in the Tetons, western glacier stoneflies were found in four streams. Wilmot can identify stonefly nymphs to genus, but they send a leg of each stonefly to the Canadian Centre for DNA Barcoding to identify them to species, he says.

Tronstad says there are currently no formal estimates as to how many western glacier stoneflies live in the Tetons, nor is there any number that has been determined as a necessary threshold to keep the insect off the endangered species list.

Tronstad says she and colleagues have written a paper on the subject that is currently under review by Freshwater Biology, a journal that publishes papers on all aspects of the ecology of inland surface waters, including rivers and lakes, connected ground waters, flood plains and other freshwater wetlands.

Her research colleagues are Joe Giersch, an aquatic entomologist at the Northern Rocky Mountain Science Center with the U.S. Geological Survey; Scott Hotaling, a postdoctoral researcher at Washington State University; and Deb Finn, an assistant professor of biology at Missouri State University.


WYNDD offers the most complete source of data for species and vegetation communities of management concern in Wyoming. Its mission is threefold: Identify and rank species that are priorities for management in Wyoming; amass existing data and develop new data for species needing management efforts, and for Wyoming vegetation types; and distribute these data upon request, under the philosophy that the best decisions regarding natural resources will be made only when everyone has access to complete and current scientific data.

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