Adult Flies (Diptera)

Chrysomya megacephalaThe Diptera are the true flies. The Diptera is one of the largest orders in the class Insecta, with over 120,000 described species. The larvae (maggots or grubs) are completely different in structure and behaviour to the winged adults and, as a result, dipterous flies can be parasites as larvae or adults, but they are rarely parasites in both life-cycle stages.

Adult flies of veterinary importance may feed on blood, sweat, skin secretions, tears, saliva, urine or faeces of the domestic animals to which they are attracted. They may do this either by puncturing the skin directly, in which case they are known as biting flies, or by scavenging at the surface of the skin, wounds or body orifices, in which case they may be classified as non-biting or nuisance flies.

The biting flies may cause particularly acute problems through their blood-feeding habit and fly populations can become so great that blood loss is significant. Biting flies may act as biological vectors for a range of pathogenic diseases and both biting and non-biting flies may also be mechanical vectors of disease. Mechanical transmission may be exacerbated by the fact that some fly species inflict extremely painful bites and, therefore, are frequently disturbed by the host while blood-feeding. As a result, the flies are forced to move from host to host over a short period, thereby increasing their potential for mechanical disease transmission. The biting activities of blood-feeding flies may also provoke hypersensitivity reactions.

The activity of both biting and non-biting species of fly may be responsible for 'fly-worry' in livestock. This is the disturbance caused by the presence and attempted feeding behaviour of flies. Responses by the host may range from dramatic escape behaviour, in which self-injury can occur, to less sensational movement into shade or simply stamping and tail switching. However, all these changes in behaviour result in reduced time spent feeding and decreased performance.

Key research group publications

Howard, J.J. & Wall, R. (1996) Control of the house fly, Musca domestica, in livestock units: current techniques and future prospects. Agricultural Zoology Reviews, 7, 247-265.

Howard, J.J. & Wall, R. (1996) Autosterilization of the housefly, Musca domestica, in poultry houses in northern India. Bulletin of Entomological Research, 86, 363-367.

Wall, R., Howard, J.J. & Bindu, J. (2001) The seasonal abundance of flies infesting drying fish in southwest India. Journal of Applied Ecology, 38, 339-348.

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