Rare Species Guide

  Basis for Listing

Until recently, Hydroptila quinola (a species of purse casemaker caddisfly) was known in Minnesota from only a single collection made in 1965 in Lake County (Northern Superior Uplands Section). In 1999, during an extensive collecting effort, adults were also located in Reilly Brook and Lost River in Koochiching County (Northern Minnesota and Ontario Peatlands Section) and in Rose Creek in Mower County (Minnesota and Northeast Iowa Morainal Section), thus confirming the extant status of this species in Minnesota. The Minnesota populations are over 1000 km (620 mi.) from the remainder of the species’ distribution in the eastern and southeastern U.S. and may constitute the western extent of its range.  Due to the few documented populations in Minnesota and the vulnerability of the Rose Creek population to human disturbance, Hydroptila quinola was listed as a special concern species in 2013.

  Description

The larva of H. quinola is unknown. Mature larvae of Hydroptila range 3–5 mm (0.1-0.2 in.) in length. They have a thickened abdomen with darker head and thorax. Immature larvae are free-living. Mature larvae build a case composed of two silken valves covered with small sand or silt particles. Adults of H. quinola are light brown in color and around 4 mm (0.2 in.).  Macroscopically, they are indistinguishable from the several dozen other species of Hydroptilidae known from the state. Adults can be definitively identified only by a close examination of the terminal abdominal segments under a microscope. Houghton (2012) has developed an identification manual and key to the caddisflies of Minnesota.

  Habitat

Little is known about the specific habitat needs of this species beyond the dependence of the larva on single-celled algae as a food source. All collection sites are undisturbed low-gradient, silt-bottomed, 3rd- to 4th-order streams.

  Biology / Life History

Little is known about the specific life cycle of H. quinola. Larvae probably live for a year under the water feeding on algal cells before emerging as winged adults in the summer. Adults from northern Minnesota were collected in July while adults from southern Minnesota were collected in September.

  Conservation / Management

It is difficult to speculate on the specific conservation needs of this species due to a lack of basic research. Two of the recent collecting sites of H. quinola were undisturbed streams protected by state forest. Any future development of the riparian corridor of these streams or any changes that would decrease water quality or increase water temperature should be approached cautiously to preserve this isolated population. Further research is necessary to identify any additional populations of the species as well as its specific habitat needs.

  References and Additional Information

Blickle, R. L. 1979. Hydroptilidae (Trichoptera) of America north of Mexico. New Hampshire Agricultural Experiment Station Bulletin 509. University of New Hampshire, Durham. pp. 1-101.

Houghton, David C. 2012. Biological diversity of the Minnesota caddisflies (Insecta, Trichoptera). ZooKeys 189:1-389.

Houghton, D. C. 2007. The effects of landscape-level disturbance on the composition of Minnesota caddisfly (Insecta: Trichoptera) trophic functional groups: evidence for ecosystem homogenization. Environmental Monitoring and Assessment 135(1-3):253-264.

Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.

Minnesota Department of Natural Resources. 2005. Field guide to the native plant communities of Minnesota: the eastern broadleaf forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 394 pp.

University of Minnesota Department of Entomology Insect Collection. 2009. UMSP Trichoptera: caddisflies. University of Minnesota, St. Paul. <http://www.entomology.umn.edu/museum/databases/>. Accessed 05 August 2009.

Wiggins, G. B. 1996. Larvae of the North American caddisfly genera (Trichoptera), Second edition. University of Toronto Press, Ontario, Canada. 457 pp.