Blow-fly
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Blow-flies (also frequently spelled blow flies or blowflies) are members of the family Calliphoridae of flies (Diptera). Flies in this family are often metallic in appearance.
Some members of this family are known as bluebottles, clusterflies or greenbottles. The name blow-fly comes from an older English term for meat that had eggs laid on it, which was said to be fly blown. Blow-flies are usually the first insect to come in contact with a dead animal.
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[edit] Identifying characteristics for the family Calliphoridae
Antennae 3-segmented with an arista; vein Rs 2-branched, frontal suture present, calypters well developed. Body metallic blue, green, or black. Arista plumose for entire length. Two notopleural bristles. Hindmost posthumeral bristle located lateral to presutural bristle.
For a pictorial atlas explaining these terms go to [1]
- Key to the Calyptrate families
- Useful site for diagnostic features. (In French
- Japanese Calliphoridae
The family is divided into subfamilies, the Calliphorinae, and the Chrysomyinae, which between them contain about 23 genera.
[edit] Biology
Blowflies have caught the interest of researchers in a variety of fields, although the large body of literature on calliphorids has been concentrated on solving the problem of myiasis in livestock. It is estimated that the sheep blowfly Lucilia cuprina causes the Australian sheep industry over $170 million a year in losses. While much of the biology of these flies has been studied in the laboratory, the natural life history of the blowflies remains a largely untapped body of research.
Adult blow-flies are occasional pollinators, being attracted to flowers with a strong odor resembling rotting meat, such as the American pawpaw or Dead Horse Arum. There is little doubt that these flies utilize nectar as a source of carbohydrates to fuel flight, but just how and when this happens is unknown.
Larvae of most species are scavengers of carrion and dung and most likely constitute the majority of the maggots found in such material, although it is not uncommon for them to be found in close associate with other dipterous larvae from the families Sarcophagidae, Muscidae, and many other acalyptrate muscoid flies.
Most species of blowflies studied thus far are anautogenous; a female requires a substantial amount of protein to develop mature eggs within her ovaries (about 800 µg per pair of ovaries in Phormia regina). The current theory is that females visit carrion both for protein and egg laying, but this remains to be proven. Blow-fly eggs are approximately 1.5 mm x 0.4 mm, are yellowish or white, and when laid, look like rice balls. While the female blow-fly typically lays 150-200 eggs per batch, she is usually iteroparous, laying around 2,000 eggs during the course of her life. The sex ratio of blowfly eggs is usually 50:50, but one interesting exception is currently documented in the literature. Females from two species of the genus Chrysomya (C. rufifaces and C. albiceps) are either arrhenogenic (laying only male offspring) or thelygenic (laying only female offspring).
Hatching from an egg to the first larval stage takes about 8 hours to one day. Larvae have three stages of development (called instars); each stage is separated by a molting event.The instars are separable by examining the posterior spiracles, or openings to the breathing system [2]. The larvae use proteolytic enzymes in their excreta (as well as mechanical grinding by mouth hooks) to break down proteins on the livestock or corpse they are feeding on. Blowflies are poikilothermic, which is to say that the rate at which they grow and develop is highly dependent on temperature and species. Under room temperature (about 30 degrees celsius) the black blowfly Phormia regina can go from egg to pupa in 150-266 hours (6 to 11 days). When the third stage is complete the pupa will leave the corpse and burrow into the ground, emerging as an adult 7 to 14 days later.
Since development is highly predictable if the ambient temperature is known, blow-flies are considered a valuable tool in forensic science. Traditional estimations of time since death (namely rigor mortis and algor mortis) are generally unreliable after 72 hours and often entomologists are the only officials capable of generating an accurate approximate time interval. The specialized discipline related to this practice is known as forensic entomology [3]
Blowfly maggots have also been used successfully in the treatment of badly infected wounds: see maggot therapy.
[edit] Other information
The Primary Screwworm (Cochliomyia hominivorax) once a major pest in southern United States, has been eradicated through massive release of sterilized males. See Sterile insect technique.
Adults may vector pathogens of diseases such as dysentery.
Calliphora vicina and Cynomya mortuorum are important flies of forensic entomology.
[edit] Diversity
Worldwide, there are 1100 species of blowflies, with 228 species in the Neotropics, but very numerous species in Africa and Southern Europe.
[edit] Identification
Fritz Konrad Ernst Zumpt Calliphorinae, in Lindner, E. Fliegen Palaearkt. Reg. 64i, 140 p. (1956)
Fan, C.T. Key to the common synanthropic flies of China. Peking [= Beijing]. xv + 330 p. In Chinese but really excellent illustrations. (1965).
Kano, R. and Shinonaga, S. Calliphoridae (Insecta: Diptera) (Fauna Japonica) , Tokyo Biogeographical Society of Japan, Tokyo.( 1968). In English.
Rognes, K. Blowflies (Diptera: Calliphoridae) of Fennoscandia and Denmark. Fauna Entomologica Scandinavica, Volume 24. E. J. Brill/Scandinavian Science Press Ltd. Leiden.(1991).
[edit] Species lists
[edit] External links
[edit] Genera
(incomplete list)
Auchneromyia (ectoparasitic)
Bengalia
Bluebottles: Calliphora, Blue bottle fly
Callitroga
Old World screw-worms: Chrysomya
New World screw-worms: Cochliomyia
Compsomyiops
Tumbu flies: Cordylobia
Cynomya
Euphumosia
Hemipyrellia
Lucilia
Melinda
Metallea
Onesia
Greenbottles: Phaenicia
Phormia
Phumosia
Cluster flies: Pollenia
Polleniopsis
Protophormia
Rhinia
Stilbomyella
Tainanina
Xenocalliphora
![[2]](http://www.smlc.asso.fr/smlc/dmla/entomologie/diaporama/images/08.jpg){kind=link}