Calliphora vicina is a member of the family Calliphoridae, which includes blow-flies and bottle flies. These flies are important in the field of forensic entomology. C. vicina is currently one of the most entomologically important fly species because of its consistent time of arrival and colonization of the body following death.
C. vicina is known as a blue bottle fly because of the metallic blue-gray coloration of its thorax and abdomen. It is distinguished from the commonly known C. vomitoria by its bright orange cheeks. The blue bottle fly is approximately 10-11 mm in length. The sclerite at the base of the coxa are yellow or orange. By chaetotaxy, the study of bristle arrangement, Calliphorids are characterized by having black bristles on the meron and two to three bristles on the notopleuron.
The similarities between the different species of Calliphora can make identification of immature stages nearly impossible. From the first instar to the pupa stage C. vicina is identical to that of C. vomitoria.
C. vicina goes through five generations in a year at a threshold temperature of 27˚ C (81˚ F). A female C. vicina can lay up to 300 eggs, on fresh carrion or on open wounds. The larvae go through three instar stages. The first instar hatches in approximately 24 hours after the eggs are laid. It goes through its second instar in 20 hours and its third instar in 48 hours. Under favorable conditions, the larvae feed for about three to four days. When the larvae complete their development, they disperse to find an adequate place to pupate. The C. vicina pupa stage last about 11 days. At 27˚ C, C. vicina’s life cycle lasts approximately 18 days.
Climatic factors, such as temperature, are known to influence egg-laying and development of instar-larvae. In warmer weather the life cycle can last a little less, and in cooler temperatures the life cycle takes a little longer. Knowing the duration between the three instars and pupa stage and post-feeding larval dispersal can be useful to determine the post mortem interval in a criminal case.
C. vicina plays a major role in corpse colonization during the winter months, with less of a presence during the warmer months when temperature is less of a constraint. This fly has a lower threshold temperature for flight activity than other blow-flies, allowing for greater prevalence during colder periods. This period of activity must be considered when evaluating the presence or absence of this fly.
When using the age of maggots to determine the PMI, the time before arrival is an important factor. The succession of C. vicina involves the arrival of adults two days after death. Therefore, two days must be added to the maximum age determined for flies found on the body.
Some knowledge regarding C. vicina behavior is well known. Case studies have shown that it is not the first species in arrival. However, it does appear one to two days before Phaenicia sericata. However, determining PMI is an intricate process because there is still much that we do not know about C. vicina behavior. For instance, it is a long held belief that the species is not nocturnally active. Recently, however, it has been shown that C. vicina is indeed active at night under certain experimental conditions.
Bluebottle flies: calliphora vicina & calliphora vomitoria (diptera: calliphoridae).(Pest Spotlight ARMING PMPs WITH KNOWLEDGE)
May 01, 2010; Bluebottle (blue blow) flies rank among the largest of the filth flies pest management professionals (PMPs) encounter at...