Calliphora species
Description
These are the familiar bluebottles and are large (6-14mm), blue, bristly flies, of which there are numerous species throughout the world.
Identification of adults and larvae to species is difficult and generally requires assistance from an expert. Additionally the taxonomic limits of Calliphora are not well understood and a phylogenetic review is needed.
Biology
Bluebottles are typically flies of shady situations and were originally probably an essential ecological component of wooded country. Females are attracted for oviposition to any decaying animal matter, of which carrion is most suitable. All species are oviparous, although delayed oviposition may result in larviposition of single precocious larvae (Wells & King, 2001). Adults visit flowers, faeces and dead animals. Larvae are saprophagous in decaying animal matter, which explains the trend towards an occasional facultative parasitism. Many species are involved in human and animal myiasis. The genus is of great medical, hygiene and forensic importance. Forensically they are the most important flies involved in cadaver succession in temperate regions, giving best indication of minimum post-mortem interval (Donovan et al 2006; Amendt et al, 2007).
Adult Calliphora will commence oviposition 4-5 days after emergence, at 24 °C. Blowfly females have excellent olfactory senses and are very able and persistent in seeking suitable oviposition sites. Eggs can be alid on a body almost immediately after death if conditions are good (season and situation of the corpse), but oviposition can be delayed by weeks or months in poor conditions. A female will lay up to 300 eggs in the natural orifices and crevices in the skin. The eggs are white, slightly curved, and about 1.7 mm long. When the eggs hatch the young larvae immediately try to penetrate the tissues via natural and unnatural openings (e.g. body orifices & wounds). The development rates of the immature stages are temperature dependent and will be strongly influenced by environmental conditions. On reaching maturity the larvae leave the corpse in large numbers and search for suitable pupation sites, usually in the top 10cm of the soil up to a distance of 6-7m from the corpse.
Calliphora species are usually only involved in myiasis as secondary species, but C. vicina, in particular, may be a primary invader of mammals (Zumpt, 1965; Smith, 1986) and even reptiles (Sales et al, 2003).
Distribution
The genus is known from all zoogeographic regions but is best represented in the Holarctic and Australian regions.
References
- Amendt, J., Campobasso, C., Gaudry, E., Reiter, C., LeBlanc, H. and HALL, M. (2007). Best practice in forensic entomology – standards and guidelines. International Journal of Legal Medicine 121: 90-104.
- Donovan, S.E., HALL, M.J.R., Turner, B.D. and Moncrieff, C.B. (2006). Larval growth rates of the blowfly, Calliphora vicina, over a range of temperatures. Medical & Veterinary Entomology 20: 1-9.
- Rognes, K. (1991). Blowflies (Diptera, Calliphoridae) of Fennoscandia and Denmark. Fauna Entomologica Scandinavica. Vol. 24, pub. E.J. Brill/Scandinavian Science Press Ltd.
- Sales, M.J., Ferrar, D., Castellà, J., Borràs, D. and Hall, M.J.R. (2003). Myiasis in two Hermann’s tortoises (Testudo hermanni). The Veterinary Record 153: 600-601.
- Smith, K.G.V. 1986. A manual of forensic entomology. London, British Museum (Natural History). 205 pp.
- Wells, J.D. and King, J. (2001). Incidence of precocious egg development in flies of forensic importance (Calliphoridae). Pan-Pacific Entomologist 77: 235-239.
- Zumpt F. (1965). Myiasis in Man and Animals in the Old World. Butterworths, London,UK, 267 pp.
