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{{nofootnotes|date=March 2008}} {{Multiple issues | orphan = March 2008 | essay = March 2008 | clean up = March 2008 | wikify = March 2008 }} The species Phormia regina, more commonly known as the black blow fly, belongs to the blow fly family Calliphoridae. Although some authorities merge both the blow fly group (Callipohoridae) and the flesh fly group (Sarcophagidae) together in the family Metopiidae, key distinguishable physical traits allow for this separation. (borer and Delong)

Being a member of the order diptera (the fly order), it is attributed by the presence of only its pair of fore wings while the pair of hind wings has been highly reduced to halteres. These halteres function in aiding in stability and maneuverability during flight. (Borrer and Delong) Blow flies are about the size of a house fly or a little larger, many are metallic blue or green. Key characteristics of this species include black gena, mostly white calypteres and anterior thoracic spiracles that appear to be orange yellow due to it being surrounded by bright orange setae. (2 sources Rognes and Whitworth)

Physiology

The blowfly is not entirely specialized when it comes to its physiology. Like most other flies the blowfly feeds via sponging having functional or non-functional mouthparts. They are known to feed on various foods, with emphasis on nectar, honey-dew, and the liquid products of decomposition. (Watson 2003) Wings of the fly are specialized having a sharp bend halfway through the wing and they are also known to have a well developed calypter. One physiological feature that characterizes the Phormia regina is that the fly is poikilothermic; the growth and development of the fly is dependent on temperature. At room temperature, the egg to pupil stage last approximately 6-11 hours. When there is an increase in temperature of the surrounding environment, typically metabolic rates of the blow fly increase, and in case cause an increase of growth and development. (Kirkpatrick, 2004) In addition to an increase in the growth and development, temperature has also a profound impact on female oviposition. (Greenberg 1990) It is key to note the fluctuations between diurnal and nocturnal temperatures. Typically blow flies will oviposit in the daytime due to the increase of temperature.

It is important to note the larval stage of the blowfly, due to its importance in forensics. The larvae have posterior spiracles, small openings on the back that are used for the intake of oxygen. Larvae are also equipped with mouth hooks that are used for the break down of proteins when feeding. Another mechanism used for the breakdown of these proteins is the proteolytic enzyme (Haub and Fletcher).

Forensic Importance

Phormia regina is a very important species in medicocriminal entomology, an area in forensic entomology which involves the calling upon of entomologists to aid with arthropod evidence in criminal investigations (Byrd and Castner 2001). This aspect of forensic science stresses utilizing arthropod evidence in solving crimes most often of a violent nature using two ideal approaches. One approach takes into account the general succession of arthropod communities to aid in estimation of post mortem interval, and the second factors in environmental influences in the development of arthropods (Byrd and Castner 2001). With knowledge of the regional insect fauna and times of carrion colonization, the insect gathering associated with the remains can be analyzed to determine a window of time in which death took place. The time elapsed since death before a corpse is discovered, referred to as post mortem interval or PMI, is critical for investigations. Post mortem interval relies on an entomologist’s ability to correlate the species or stage of development of arthropods, namely Phormia regina, to an elapsed period between a person’s death and the discovery of his/her body (Byrd and Castner 2001).

Blow flies are usually the first insects to colonize a body, frequently within minutes after death (Catts and Goff 1992). Phormia regina adults and larvae are attracted to the body because during decomposition, the remains go through rapid physical, biological, and chemical changes. If a corpse is found, the early stages of diptera present may be used in determining the post mortem interval (PMI) by reverse estimation of the time is would take for eggs to have been deposited and larvae to have developed to the stage they were collected while taking into account environmental factors. The use of maggot age and development can give a date of death accurate to a day or less and is used in the first few weeks after death. Blow flies will lay their eggs on the corpse, usually in a wound, if present, or in any of the natural orifices (Anderson). Therefore, after a single blowfly generation has been completed, the time of death is determined using the first method, that of insect succession.

Research is being conducted to further perfect the dating of a post mortem interval. A study done by Greenberg suggests that Phormia regina occasionally oviposit on carrion during nocturnal hours only when certain conditions are met( Greenberg 2003). A similar study performed in Central Texas (Kirckpatrick 2004) found that a combination of artificial lighting, warm temperatures, and the onset of low-pressure atmospheric conditions encourages nocturnal oviposition in Phormia regina. This knowledge of the effects of nocturnal temperatures on blow fly occurrence and oviposition behavior will lead to more accurate estimates of the post mortem interval related to deaths, therefore, an abundance of research is needed in order to assign a precise PMI.

Discovery

Much of the research that was invested in blowflies is attributed to the 1800’s German scientist Johann Wilhelm Meigen. Meigens career works was mainly involved in the taxonomical aspect of identifying different species of diptera. Spending a lot of time classifying species based on wing ventilation as well as, antennae, he discovered that this was not sufficient enough to classify these dipteran species. He then reasoned that species can only identified by combination of characteristics; this technique later became known as the eclectic method.

References

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Further reading

• Anderson, G.S. Forensic Entomology: the use of insects in death investigations. [1]
• Byrd, J. H., and J. L. Castner. 2001. Forensic entomology : The utility of arthropods in legal investigations. CRC Press, New York.
• Catts, E. P., and M. L. Goff. 1992. Forensic entomology in criminal investigations. Ann. Rev. Entomol. 37 : 253-272.
• Fletcher F., Haub J.G. Digestions in blowfly larvae, Phormia regina meigen, used in the treatment of osteomyelitis. Ohio State Univeristy. phttps://kb.osu.edu/dspace/bitstream/1811/2619/1/V33N02_101.pdf]
• Greenberg, B. 1990. Nocturnal oviposition behavior of blow flies (Diptera: Calliphoridae). J. Med. Entomol. 27 (5) : 807-810.
• Kirkpatrick, R. S. Nocturnal light and temperature influences on necrophagous, carrion-associatingblow fly species of forensic importance in Central Texas. TAMU Undergrad. J. Sci.
• Rognes, Knut. 1991. Blowflies (Diptera, Calliphoridae) of Fennoscandia and Denmark. E.J. Brill/Scandinavian Science Ltd., 272pp.
• Watson L., Dallwitz M.J., British Insects: the Families of Diptera.[2]
• Whitworth, Terry. 2006. Keys to the Genera and Species of the Blow Flies (Diptera:Calliphoridae) of America North of Mexico. PROC. ENTOL. SOC. WASH. 30 June. 108(3), Pp.629-725

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