The fly (musca domestica) are commonly found where people work and live because of the warm environment and the ready supply of food.
The female fly can lay several batches of eggs with up to 150 eggs in each batch. Their eggs are laid in moist or rotting matter (household rubbish, compost, manure) and once hatched the maggots complete their development. The fly can reach maturity in about two weeks when the weather is warm.
House flies have sponging mouthparts and they eat by turning the food to liquid with their saliva and sucking it back in.
Although they cannot bite, flies are known to transmit causes of diarrhea, dysentery and eye infections and intestinal worms and can cause gastroenteritis. This isn’t surprising given the places where they have come from.