Summary: Houseflies in dairy farms can be a concern since they could play a crucial role in increased bacterial counts in milk and the potential occurrence of transmitted diseases that affect public and animal health. This study evaluated the bacterial communities associated with houseflies captured on a dairy farm in New York State. A total of 101 flies were collected at 3 farm sites: hospital pen, calf hutches, and milking parlor. Each housefly was tested by bacteriological analysis for microbial identification, and a total of 304 bacterial isolates were obtained. Twelve percent of the identified organisms are well known to affect dairy farms. We identified 26 bacterial species with implications for animal health since these are mastitis-causing pathogens; 5 bacteria are considered foodborne pathogens and, for this reason, represent a concern for human health, and last, but not least, we identified 5 milk spoilage bacteria species that affect the quality of dairy products.