First Report of Coenosia attenuata Stein (Diptera: Muscidae), an Old World 'Hunter Fly' in North America

The Palearctic muscid Coenosia attenuata Stein is reported for the first time in North America based on collections from the U.S.A. and Canada. Adult flies were collected from commercial greenhouses in Erie, Monroe, Onondaga, Suffolk, Tompkins, and Wayne counties of New York State and Ontario Province, Canada, and from a Malaise trap in a suburban backyard of Los Angeles County, California. A diagnosis, redescription, and photographs of the adult are provided to help distinguish it from other North American Muscidae. Its biology and habits are summarized from the European literature, and its Old World distribution is reviewed.