The triclad Phagocata gracilis (Haldeman, 1840) is reported for the first time from Michigan. Numerous individuals were first collected in 1968 in Oden Stream (T35N R4W S18), Emmet County, a cold, spring-fed fish hatchery outlet stream. Ecological data collected over a two-month period and observations on planarian populations are presented. Other species found in the stream include Dugesia dorotocephala, D. tigrina, Phagocata morgani, P. velata, and Procotyla fluviatilis; Dugesia dorotocephala may be unable to compete with Phagocata gracilis.