Forty-seven species of flies have been reliably associated with filthy conditions that might allow the spread of foodborne pathogens. These are categorized as "filth flies." Of that 47, only 21 species represent a potential threat to human health as scientifically proven causative agents of foodborne myiasis or as carriers of enteropathogenicEscherichia coli, Salmonella, Shigella,and other foodborne pathogens. These 21 species are categorized as "disease-causing flies" based on strict scientific criteria. The criteria are association withE. coli, Salmonella,ANDShigella;synanthropy; endophily; communicative behavior; attraction to both excrement and food products; and recognition by authorities as a potential health hazard. Within Hazard Analysis and Critical Control Point and other U.S. Food and Drug Administration regulatory frameworks, disease-causing flies are contributing factors to the spread of foodborne disease that require preventive and corrective actions as appropriate under Sanitation Standard Operating Procedures, Good Manufacturing Practices, or pest control programs.