Adult house flies feed and breed in a variety of microbe-rich habitats and serve as vectors for human and animal pathogens. To better understand their role in harbouring and disseminating bacteria, we characterized the composition and diversity of bacterial communities in the gut of female house flies collected from three different habitats in Kansas: agricultural (dairy farm), urban (business area dumpsters) and mixed (business located between residential and animal agriculture areas). Bacterial community composition and diversity were influenced more by the house flies' habitat than by sampling time. The most abundant taxa were also highly prevalent in the house flies collected from all three habitats, potentially representing a 'core microbiome' attributable to the fly's trophic and reproductive associations with substrates and food sources comprised of decaying matter and/or animal waste. Bacterial taxa associated with vertebrate guts/faeces and potential pathogens were highly abundant in agricultural fly microbial communities. Interestingly, taxa of potential pathogens were highly abundant in flies from the mixed and urban sites. House flies harboured diverse bacterial communities influenced by the habitat in which they reside, including potential human and animal pathogens, further bolstering their role in the dissemination of pathogens, and indicating their utility for pathogen surveillance.