Here's the third of the four flies from my upcoming "Nature's Wonders Flies" ruining some perfectly good pizza... The housefly is probably the insect with the widest distribution in the world; it is largely associated with humans and has accompanied them around the globe. It is present in the Arctic, as well as in the tropics, where it is abundant. It is present in all populated parts of Europe, Asia, Africa, Australasia, and the Americas. It possibly originated in the Middle East, and spread around the world as a commensal of humans. Houseflies are often considered a nuisance, disturbing people while at leisure and at work, but they are disliked principally because of their habits of contaminating foodstuffs. They alternate between breeding and feeding in dirty places. During the process of feeding on human foods, they soften the food with saliva and deposit their feces, creating a health hazard.