Just like cockroaches, rodents and ants, flies also play a role in cycling organic material and spreading pathogens, such as Campylobacter and Salmonella bacteria. Controlling them is more difficult, because of their size and ability to fly through even the smallest cracks. Also, their eggs and larvae can be carried on food products and packages from food providers. That is why the sanitation of food and not bringing containers inside a food plant, hospital, or restaurant are so important.
Depending on the fly, some can breed in trash cans, organic matter spilled on the floor, dead rodents inside the structure, filthy drains and sinks holes, and rotten food.
They belong to the Diptera Order, with halters being their second pair of wings, and mouthparts varying from piercing/sucking (stable flies) to sponging (house flies). Adults generally eat liquids or small particles of food, because they don’t have chewing mouthparts, like their larvae. They are holometabolous insects (egg-larva A.K.A. maggot-pupa-adult) and their longest period of life is generally the larval stage; that is why it is so important to find where they are breeding and control them in their immature stage. Larvae will not be found in exactly the same places where adults fly and rest. For example, adult house and Calliphoridae flies may rest on walls above trash cans and their larvae would be inside, underneath or on the borders of the trash cans, wherever the food source is found.