General characteristics and life cycle
C. mortuorum is a deep blue-green shining metallic fly with a yellowish face and jowls, possessing a body length of 8–15 mm. [1] This fly is a cold-adapted blowfly originally named by Carl Linnaeus in 1761. [2] It lays its eggs on carrion, which provides food for the larvae and facilitates the larvae's development. The development lasts approximately 38 days. [1] As do most blow flies, or members of the family Calliphoridae, C. mortuorum has a life cycle that includes an egg stage, three larval instars, and a pupal form before becoming an adult, or imago. [3] Insects with this kind of life cycle have holometabolous development, meaning that the larval stage looks completely different from the adult. [4] Each of these stages has identifying characteristics that are unique to this species.
Egg
As an egg, it has been described as a whitish cylinder with a tapered anterior end and blunt posterior end. The egg is generally 1.62 to 1.75 mm in length and 0.5–0.7 mm in width. [2] These eggs are generally larger than other calliphorid eggs. On the dorsal surface of the egg, there are two hatching pleats on either side of the chorion, which acts as a plastron. Sometimes, the eggs can be difficult to separate from eggs of other species, so great care needs to be taken when using these eggs for forensic studies. [5]
Larvae
The larval stage is broken up into three instars; and, each instar has 12 segments. The first instar is about 1.87 to 2.13 mm in length, and has complete anterior spinal bands on segments 2 through 8 and complete posterior bands on segments 7 through 11. Also, the skeleton of this instar has a lateral plate on which the narrowest portion is smaller than the length of the mouth hook; this is the same for the second instar. The second instar, however, is 2.74 to 3.75 mm in length, and has complete anterior spinal bands on segments 2 through 9 and complete posterior spinal bands on segments 8 through 11. Lastly, the third instar has been found to be 13.12 to 14.00 mm in length with complete anterior spinal bands on segments 2 through 8 and complete posterior spinal bands on segments 10 through 11. It can be distinguished from other third instar larvae in that the dorsal margin of its tooth is mostly straight, and then curves suddenly at the tip.
Pupae
The pupae of C. mortuorum are generally longer than pupae of Calliphora species, ranging from 8.49 to 9.75 mm. [2]
Ecology
C. mortuorum lives on woodland edges, meadows, and other places with flowers in Europe and Asia. [1] It has been found in the northern regions of both Europe and North America, and east to Turkestan. Also, it can be found in a wide variety of carrion from rotting fish to Arctic vole carcasses. [2] Within England, it has been found mostly in upland areas – above 500 m. In these upland areas, it is mostly found on small carcasses, such as mice and other small mammals; occasionally, it will be found on larger carcasses like sheep. [7] In the absence of carrion, excrement provides a food source. The adults feed on pollen, and are found from May to September. [1] C. mortuorum has not been shown to cause myiasis. [2]
As a cold weather fly, it is expected to show up in the fall months. However, one study found the presence of C. mortuorum on a mouse carcass in mid-August, and on a sheep carcass in mid-June. [8]
Uses in forensic entomology
The use of C. mortuorum in the judicial system is most commonly applied to the medicocriminal branch of forensic entomology. It is often useful in estimating the post-mortem interval of a human cadaver. By studying the morphology and stage of development of the C. mortuorum obtained from a body, one can determine an estimate of a time of death for that body. Plenty of variables play into the use of insects in a criminal investigation, including temperature, certain chemicals, or location, but determining an arthropod's stage of development on a corpse proves to be an accurate technique in estimating a time of death.
Calliphoridae eggs, like C. mortuorum eggs, usually hatch twenty-four to forty-eight hours after being laid. These specimens, once hatched, undergo three instars in their larval stage, which can take anywhere from four to twenty-one days. Another three to fourteen days account for the blow fly's pre-pupae stage, and, finally, the pupae stage can take an additional three to twenty days. Depending on certain variables, a forensic entomologist can pinpoint which stage of development a C. mortuorum is in, and how long it and the carcass it is feeding on have been there. [2]
Current research
C. mortuorum, as well as many other Calliphorid species are forensically important due to their predictable succession within a decomposing corpse, which can provide important information relating to time and place of death. In order to predict a valid time estimation, highly accurate species identification is essential. Using morphological methods to identify differences between such closely related species can often be very difficult, especially if the fly or larvae has been poorly preserved. With current technology, DNA typing of these insects offers a quick and reliable alternative.
In Europe and parts of the U.S., a study has been conducted collecting DNA sequence data over a range of commonly encountered forensically important Calliphoridae species. One species observed was the C. mortuorum. This specimen was collected in Durham, UK. Flies used in this study were caught with liver-baited sticky traps. High quality DNA was extracted from these flies, and the genetic marker used in this study was the large sub-unit (lsu) ribosomal RNA gene. (This lsu rRNA gene has also been used in studies of evolutionary analysis of other organisms.) The DNA analysis collected in this study provides insight to different evolutionary patterns apparent in the family Calliphoridae, which can possibly provide a measure of the degree of genetic variation likely to be encountered within taxonomic groups of different forensic usefulness. This study provides the first documented molecular based phylogenic analysis of the blowfly species. This research and more studies to come in the future will greatly assist the identification of larvae and adult insect species, which may play a great role in medicocriminal forensic entomology. [11]
Forensic entomology is a branch of forensic science that uses insects found on corpses to help solve criminal cases. This includes studying the types of insects commonly found on cadavers, their life cycles, their presence in different environments, and how insect assemblages change with decomposition.
The Calliphoridae are a family of insects in the order Diptera, with almost 1,900 known species. The maggot larvae, often used as fishing bait, are known as gentles. The family is known to be polyphyletic, but much remains disputed regarding proper treatment of the constituent taxa, some of which are occasionally accorded family status.
The common green bottle fly is a blowfly found in most areas of the world and is the most well-known of the numerous green bottle fly species. Its body is 10–14 mm (0.39–0.55 in) in length – slightly larger than a house fly – and has brilliant, metallic, blue-green or golden coloration with black markings. It has short, sparse, black bristles (setae) and three cross-grooves on the thorax. The wings are clear with light brown veins, and the legs and antennae are black. The larvae of the fly may be used for maggot therapy, are commonly used in forensic entomology, and can be the cause of myiasis in livestock and pets. The common green bottle fly emerges in the spring for mating.
Chrysomya putoria, also known as the tropical African latrine blowfly, is a fly species belonging to the blowfly family, Calliphoridae.C. putoria is native to Africa and has recently spread to the Americas. These flies pose significant health risks, especially due to their close association with human settlements. Adult flies can carry pathogens, while larvae may cause myiasis by growing and feeding on the flesh of domestic animals and humans. Other myiasis-causing flies in the same genus are C. bezziana and C. megacephala. C. putoria and other flies that feed on decomposing tissue are used as important tools in forensic entomology to establish the post-mortem interval, or the time elapsed since death.
Calliphora vomitoria, known as the blue bottle fly, orange-bearded blue bottle, or bottlebee, is a species of blow fly, a species in the family Calliphoridae. Calliphora vomitoria is the type species of the genus Calliphora. It is common throughout many continents including Europe, Americas, and Africa. They are fairly large flies, nearly twice the size of the housefly, with a metallic blue abdomen and long orange setae on the gena.
Chrysomya is an Old World blow fly genus of the family Calliphoridae. The genus Chrysomya contains a number of species including Chrysomya rufifacies and Chrysomya megacephala. The term “Old World blow fly” is a derivative of both the associated family, Calliphoridae, and the belief that the genus Chrysomya originated in Asia and migrated to North America only relatively recently. Chrysomya’s primary importance to the field of medico-criminal forensic entomology is due to the genus’ reliable life cycle, allowing investigators to accurately develop a postmortem interval. Chrysomya adults are typically metallic colored with thick setae on the meron and plumose arista. The name comes from the word chrysos, meaning “golden” in reference to the metallic sheen of the genus’ species, and -mya, a derivation from the word myia, meaning “fly”.
Forensic entomological decomposition is how insects decompose and what that means for timing and information in criminal investigations. Medicolegal entomology is a branch of forensic entomology that applies the study of insects to criminal investigations, and is commonly used in death investigations for estimating the post-mortem interval (PMI). One method of obtaining this estimate uses the time and pattern of arthropod colonization. This method will provide an estimation of the period of insect activity, which may or may not correlate exactly with the time of death. While insect successional data may not provide as accurate an estimate during the early stages of decomposition as developmental data, it is applicable for later decompositional stages and can be accurate for periods up to a few years.
Lucilia illustris is a member of the fly family Calliphoridae, commonly known as a blow fly. Along with several other species, L. illustris is commonly referred to as a green bottle fly. Lucilia illustris is typically 6–9 mm in length and has a metallic blue-green thorax. The larvae develop in three instars, each with unique developmental properties. The adult fly typically will feed on flowers, but the females need some sort of carrion protein in order to breed and lay eggs.
Phormia regina, the black blow fly, belongs to the blow fly family Calliphoridae and was first described by Johann Wilhelm Meigen.
Chrysomya albiceps is a species belonging to the blow fly family, Calliphoridae.
Chrysomya megacephala, more commonly known as the oriental latrine fly or oriental blue fly, is a member of the family Calliphoridae (blowflies). It is a warm-weather fly with a greenish-blue metallic box-like body. The fly infests corpses soon after death, making it important to forensic science. This fly is implicated in some public health issues; it can be the cause of myiasis, and also infects fish and livestock.
The common toad fly, Lucilia silvarum, is a member of the fly family Calliphoridae. This fly was first discovered by Johann Wilhelm Meigen in 1826 and is found most notably in European and Western Countries.
Compsomyiops callipes, previously known as Paraluclia wheeleri, is a member of the blowfly family Calliphoridae. It is a warm weather fly that can be found in southwestern parts of the United States and parts of South America. This species can be identified by its chaetotaxy, metallic blue color, club-shaped palp, and brown calypters.
Cynomya cadaverina, also known as the shiny blue bottle fly, is a member of the family Calliphoridae, which includes blow flies as well as bottle flies. In recent years, this family has become a forensically important facet in many medicocriminal investigations in the growing field of forensic entomology. C. cadaverina is specifically important in determining a post-mortem interval, as well as other important factors.
Lucilia mexicana is a species of blow fly of the family Calliphoridae, one of many species known as a green bottle fly. Its habitat range extends from southwestern North America to Brazil. L. mexicana is typically 6–9 mm in length with metallic blue-green coloring. This species is very similar in appearance to L. coeruleiviridis, the primary difference being that L. mexicana has two or more complete rows of post-ocular setae. L. mexicana has the potential to be forensically important in the stored-products and medicocriminal fields, but more research is needed for the fly to be used as evidence in criminal investigations.
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Lucilia coeruleiviridis, formerly Phaenecia coeruleiviridis, is commonly known as a green bottle fly, because of its metallic blue-green thorax and abdomen. L. coeruleiviridis was first discovered by French entomologist Pierre-Justin-Marie Macquart in 1855. It belongs to the family Calliphoridae and is one of many forensically important Diptera, as it is often found on decaying substances. L. coeruleiviridis is one of the most ubiquitous blow fly species in the southeastern United States, particularly in the spring and fall months.
Protophormia terraenovae is commonly called northern blowfly, blue-bottle fly or blue-assed fly. It is distinguished by its deep blue coloration and large size and is an important species throughout the Northern Hemisphere. This fly is notable for its economic effect as a myiasis pest of livestock and its antibiotic benefits in maggot therapy. Also of interest is P. terraenovae’s importance in forensic investigations: because of their temperature-dependent development and their prominent presence on corpses, the larvae of this species are useful in minimum post-mortem interval (mPMI) determination.
Calliphora loewi is part of the family Calliphoridae, which consisted of bottle flies and blowflies, and in the genus Calliphora, blue bottle flies. The genus can be deceiving since C. loewi is not blue. Though this species is rare, it can play an important part in forensic entomology, spreading disease, and decomposing carrion. The life cycle of C. loewi is similar to the life cycle of the genus Calliphora. Since this species is rare there has not been much research on it.
Cochliomyia macellaria, also known as the secondary screwworm, is a species of blow fly in the family Calliphoridae. These screwworms are referred to as "secondary" because they typically infest wounds after invasion by primary myiasis-causing flies. While blow flies may be found in every terrestrial habitat, C. macellaria is primarily found in the United States, American tropics, and sometimes southern Canada. They are most common in the southeastern United States in states like Florida. C. macellaria have a metallic greenish-blue thorax and a red-orange head and eyes. These adult blowflies range from 5–8 mm in size.
