House fly
organism to human populations; the housefly is always found in association with human activity. As the most common species of fly found on livestock farms [...] viruses (such as the Newcastle Disease virus), bacteria (such as Salmonella and E. coli ), protozoan parasites (such as Giardia ), and the eggs of many parasitic [...] General Houseflies are a well-known pest of farm and home. Believed to have originated in central Asia, the insect expanded its range worldwide long ago