Susan’s Purse-making Caddisfly on the Brink of Extinction

For immediate release: July 9, 2008

Dr. Celeste Mazzacano, Aquatic Conservation Coordinator,
Xerces Society for Invertebrate Conservation; 503-232-6639

Scott Hoffman Black, Executive Director,
Xerces Society for Invertebrate Conservation; 503-449-3792

Dr. Nicole Rosmarino, Wildlife Program Director,
WildEarth Guardians; 505-699-7404

Scientists, Conservationists Act to Protect an Indicator of Watershed Health

Portland, OR- A coalition of scientists and conservationists filed a petition today requesting that the U.S. Fish and Wildlife Service extend Endangered Species Act protection to Susan’s purse-making caddisfly (Ochrotrichia susanae).

Susan’s purse-making caddisfly is only known from two sites in central Colorado: Trout Creek Spring and High Park Fen. A recent status review developed by the Xerces Society for Invertebrate Conservation strongly indicates that this caddisfly is critically imperiled and may be on the brink of extinction.

Besides being extremely rare, the species is threatened by habitat damage from intensive livestock grazing, timbering projects, de-watering of spring habitats due to groundwater withdrawal by surrounding cities, and off-road recreational vehicle use.

“The science clearly shows that Susan’s purse-making caddisfly is threatened with extinction,” said Dr. Celeste Mazzacano, Aquatic Conservation Coordinator for the Xerces Society for Invertebrate Conservation. “The plight of O. susanae is really just the tip of the iceberg for spring-dependent species in the arid West, many of which are found in only one or a handful of threatened springs.”

Caddisflies such as Susan’s purse-making caddisfly are described as “indicator species,” meaning that the health of their populations signals the health of their freshwater habitats. Susan’s purse-making caddisfly is in the group called micro-caddisflies, extremely small animals that move slowly across the substrate, scraping and eating diatoms from rocks. Near the end of their larval stage the purse-making caddisfly constructs and lives in a purse-shaped case made of small pebbles. The caddisflies require relatively undisturbed habitats with good water quality, making them excellent biological indicators of watershed health.

Susan’s purse-making caddisfly is only one of the many unique species found nowhere but in Western springs, and carefully targeted management of these habitats is essential to maintain their biological integrity and sustain the diverse species they support.

Trout Creek Spring and the surrounding area are critical to the continued survival of the imperiled Susan’s purse-making caddisfly,” said Scott Hoffman Black, Executive Director of the Xerces Society for Invertebrate Conservation. “The impacts of current livestock grazing, as well as the impact from planned timber harvest could drive the Susan’s purse-making caddisfly extinct.”

Endangered Species Act protection for the caddisfly would mean that their habitat would be protected and restored.

“The Endangered Species Act is a safety net for fish and wildlife on the brink of extinction,” said Jonathan B. Ratner, Director of Western Watersheds Project Wyoming Office.” We owe it to our children and grandchildren to be good stewards of the environment and leave behind a legacy of protecting endangered species, like these caddisflies, and the special places they call home.”

The petitioners include: Dr. Boris Kondratieff, a University of Colorado entomologist and expert in aquatic insects; The Xerces Society for Invertebrate Conservation, an international nonprofit scientific organization dedicated to protecting wildlife through the conservation of invertebrates and their habitat; Western Watersheds Project, a group working to protect the health of western waters; Center for Native Ecosystems, a group dedicated to protecting native species and their habitats in the Rocky Mountain Region; and WildEarth Guardians, which protects and restores wildlife, wild rivers and wild places in the American West.

Above photo of an Island Marble butterfly by Bob Pyle