When flies feed on waste, they collect pathogens on their legs and mouths. These pathogens are then transferred to food on tables or counters when a fly lands again. Flies regurgitate on solid food then they eat the liquid. They are capable of transmitting disease when they vomit, groom themselves or just walk on surfaces.
The best way to repel flies is through simple, preventive measures. Flies prefer warm temperatures and are most active during the summer months. In order to best repel flies during this time, limit access to your home as much as possible, keeping doors and windows closed. You may also choose to screen windows, doors and vents. Keep garbage cans clean and securely closed. Keeping surfaces clean will make your home less appealing to flies.