Appearance This small, mothlike aquatic insect has two pairs of hairy wings. Caddisflies are closely related to moths and butterflies. They are perhaps best known for the distinctive cases that enclose the larvae. The cases are artistic arrangements of tiny pebbles, sand, twigs, and aquatic plants, all held together by silk. Researchers believe the Headwaters Chilostigman caddisfly's case consists of small pieces of leaves and bark.
Range and Habitat Caddisflies live in aquatic habitats such as lakes, streams, and wetlands. With its great diversity of waters, Minnesota is a caddisfly hotbed, with 285 recognized species and two more awaiting validation as new species after being discovered in the Boundary Waters. In 1974 Glenn Wiggins, from the Royal Museum of Ontario, was collecting caddisflies in Itasca State Park when he discovered 18 specimens of a caddisfly new to science. Eventually named Chilostigma itascae, it has been found only in this location. Other members of this genus occur only in Scandinavia and Finland.
Life History Researchers have found adult Chilostigman caddisflies that emerged onto the snow in the winter-true and hardy native Minnesotans. Because of this species' rarity and winter habits, they are very difficult to study, so nothing else is currently known about their life history.
Food Many caddisflies, including Chilostigman, are able to feed in very cold water in the winter-under the ice. If you want to learn about caddisflies, check out trout-fishing and fly-tying books. Because trout in coldwater streams readily feed on newly emerged adult caddisflies, many famous trout flies are made to look like caddisflies.
Status On New Year's Eve day 1995, Margot Monson, a University of Minnesota graduate student, surveyed Nicollet Creek, where the first records for the Headwaters Chilostigman caddisfly had occurred 21 years earlier. She located several males and females. Chilostigman caddisflies were still present-one of Minnesota's rarest endangered species. Funds for this survey came from the DNR Nongame Wildlife Checkoff on state tax forms. Checkoff donations help popular species such as loons, eagles, and trumpeter swans. To protect Minnesota's biodiversity, the wildlife checkoff also supports the preservation and study of lesser known but ecologically significant species such as the Headwaters Chilostigman caddisfly.
Carrol L. Henderson
DNR Nongame Wildlife Program supervisor
The Headwaters Chilostigman caddisfly lives exclusively in the Pine Moraines and Outwash Plains ecological subsection highlighted in Tomorrow's Habitat for the Wild and Rare: An Action Plan for Minnesota Wildlife. This subsection of more than 3 million acres contains large forests, hundreds of lakes, wetlands, and the Mississippi River. It harbors 89 species in greatest conservation need. Habitat loss and degradation pose the greatest risks to these species. To learn more, go to www.mndnr.gov/cwcs/subsection_profiles.html.