Arapahoe Snowfly designated as candidate for endangered species protection

The Arapahoe snowfly, an insect found in two tributaries of the Cache la Poudre River in Colorado, warrants protection under the Endangered Species Act, The U.S. Fish and Wildlife Service announced last week in a news release.

However the snowfly’s need for protection is precluded by the need to address other higher priority species and will therefore be added to the list of candidate species whose statuses are reviewed annually, according to the release.

“When a ‘warranted but precluded’ finding is made for a species, we classify it as a candidate for addition to the federal list of threatened and endangered species,” said Mike Thabault, assistant regional director of ecological services, in the release. “If we propose the Arapahoe snowfly for protection under the ESA in the future, the public will have an opportunity to comment.”

The agency completed a comprehensive status review and determined there is sufficient scientific and commercial data to propose listing the species as threatened or endangered. However due to limited resources and other priorities, the agency is precluded from beginning work immediately on a listing proposal, according to the release.

The Arapahoe snowfly is a species of insect in the order Plecoptera (stonefly). Stoneflies, including the Arapahoe snowfly, are typically found in cold, clean, well-oxygenated streams and rivers, and are sensitive to most types of pollution, according to the release.

According to the agency, the species was first discovered in 1986 in Young Gulch, a small tributary of the Cache la Poudre River in the Front Range of the Rocky Mountains of Colorado. It is a small, dark‑colored insect with both a body length and wing length of approximately 0.2 inches.

In 1988, it was identified as a new species. It was also found in a second tributary, Elkhorn Creek, approximately five miles from Young Gulch. No other populations have been found in searches of nearby tributaries, and numerous visits to Young Gulch since the species’ discovery in 1986 have failed to locate additional specimens, according to the release.

Because of that, the Service believes the species now only occurs in Elkhorn Creek.

The status review identified threats to the species including the potential present and future threat of habitat modification caused by climate change, the lack of adequate regulatory mechanisms to protect the species from impacts due to climate change, and its small population size, the release stated.

The U.S. Forest Service, which manages the lands where the Arapahoe snowfly has been located, oversees several other activities, including recreational use, forest management, and grazing, which were not found to be threatening the species at this time, according to the release.

For more information about the Arapahoe snowfly and this finding, please visit the Service’s website at