House flies normally stay within 1 mile of where they emerged due to a sustainable food source. They are normally found outside in warmer temperatures near areas that are unsanitary and filthy. They can also be found near dead animal carcasses and animal feces. When the temperatures get cooler, the house fly will try to gain access to your structure by open doors or windows or ripped screens.
Once inside, you can find them around windows, doors, ceilings, walls, by trash cans, floor drains, near light sources, or around left out food and pet food.
House flies are carriers of over 100 disease causing pathogens. They transmit these pathogens on their bodies, legs, vomit, and feces. Transmission occurs when the fly lands on food or surfaces where food is prepared.