The average lifetime for a fly is just 28 days, but a lot of damage can be done in that short period of time. While the female house fly usually only mates once in her life, she has the ability to store sperm for use later and can lay approximately 500 eggs in a lifetime. House flies in their adulthood can reach up to 7 millimeters long and usually, the female has larger wings.
House flies carry pathogens in their fecal matter and on their bodies. Those are then transferred to any surfaces and/or food the flies land on during the course of their life.