The microcaddisfly genus Ithytrichia Eaton (Trichoptera: Hydroptilidae) has been previously reported from many Great Lakes states (Illinois: Ross 1944, Ohio: Huryn and Foote 1983, Wisconsin: Hilsenhoff 1995, Pennsylvania: Moulton et al., 1999, Minnesota: Houghton et al., 2001, New York: Bode et al., 2002) and Canada (Barton and Hynes 1978), but had not previously been documented from Michigan. Ithytrichia larvae are strongly compressed laterally and have distinct lobate projections. They produce a purse-like case made of silk secretions and live on rocks and moss in lotic habitats where their ability to keep the flat side of their case against the substrate is advantageous (Wiggins 1996). Ithytrichia specimens were identified as part of a benthic macroinvertebrate community survey for the Crystal River within Sleeping Bear Dunes National Lakeshore, conducted in July and September 2004 and June 2005. The park is located along the eastern shore of Lake Michigan in Leelanau County, Michigan. Our observations in conjunction with those of White (1987) describe the river as follows: it originates in Glen Lake, passes through Fisher Lake, and empties into Lake Michigan. Total stream length is <10 km, half of which is within the park. Although the river receives ground-water input, discharge is primarily surface water from the lakes, resulting in warm, rich, hard water. Beds of submerged aquatic vegetation over a sandy substrate are extensive in certain reaches of the river, while other areas are characterized by pool-riffle-run over sand and gravel, and some segments of the stream are runs of bare sand. The low-head dam and culverts at County Road 675 provide areas of tailrace whitewater flow over cobble and gravel. Although depths range from less than 3 cm over some gravel bars to about 1.5 m in a deep run, the overall average depth of the river is about 0.3-0.6 m. Typically, the shoreline is littered with woody debris and detritus. Benthic macroinvertebrate samples were collected by D-frame dip-net. All samples were preserved in 10% buffered formalin and transported to the Great Lakes Science Center in Ann Arbor, MI, where they were sorted and identified. Trichoptera identification was based on Wiggins (1996), and representative specimens were donated to the University of Michigan Museum of Zoology, Insect Division, Trichoptera Collection. All 14 Ithytrichia specimens we encountered were larvae and were collected from a variety of substrate types and flow regimes. Whereas the literature indiVolume 118, Number 3, May and June 2007 313