Chrysomya
Encyclopedia
Chrysomya is an Old World
blow fly genus belonging to the family Calliphoridae. The Chrysomya genus 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 (blow flies), 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.
Keep in mind, however, that not all species will conform completely to these guidelines. Adults feed on many things including decaying matter, excreta, and flowers. In their six week lifespan, (specific length may differ as a result of temperature, weather, etc.) females lay egg masses typically consisting of 50-200 eggs.
Different species within this genus exhibit varying egg laying procedures. The species Chrysomya bezziana
, for example, lay their eggs exclusively on live mammals. In contrast, most Chrysomya species prefer to perform oviposition
on dead organisms. And, as with many fly genera primary and secondary myiasis
is possible but unlikely.
The genus Chrysomya contains 12 species, several of which cause primary and secondary myiases of domestic animals. The larvae of one species, Chrysomya rufifacies
, have very distinct thorn-like processes covering its entire body, giving it the common name “hairy maggot blow fly”. The hairy appearance of C. rufifacies makes it easy to distinguish 2nd and 3rd instars from close relative, Chrysomya megacephela. Although the 1st instars are fairly similar, C. megacephela are characterized by thicker spiracle hairs in the 2nd and 3rd instars.
, the results are much larger masses containing thousands of eggs that may completely cover a decomposing carcass. These eggs are typically yellowish or white in color and, when laid, look like rice balls. The eggs hatch in as little as eight hours. This of course depends on air temperature and the ability of larvae to feed on carrion, until consuming enough calories to progress through the instar stages and pupate. Once this is achieved, third instars travel away from the corpse, usually into shallow soil and pupate. During this time, the larval skin which was initially milky white actually shrinks and hardens to form a dark brown puparium. This stage may last as long as 12 days, while some adults emerge in seven to eight days, again depending on temperature. Generally the warmer the temperature, the faster the life cycle is completed. Once in adult form, C. rufifacies oviposits approximately five days after mating, and lives an average of six weeks.
is the infestation of vertebrate tissue by dipterous
larvae. These larvae feed on the dead or living tissue of their vertebrate hosts. Several species of Chrysomya are known to cause myiasis in animals and/or humans. One species, Chrysomya albiceps, feeds on only diseased tissue of a host. A second species, Chrysomya rufifacies, is a predator of primary parasites and was once used as a treatment for osteomyelitis
. Another species, Chrysomya bezziana
, is one of the most important causes of myiasis in the Old World. Cattle are the main host of this larvae, as well as humans and other domestic animals.
is thought to be a mechanical vector of various diseases due to its association with filth. C. rufifacies predation of other fly species can have a profound effect on PMI estimates and actual survivorship of the host fly species. Studies showed that predation by C. rufifacies on Cochliomyia macellaria caused a dramatic decrease in survivorship, from 36.3% to 10%.
Chrysomya rufifacies is found widespread throughout the southern US, including southern California, Arizona, Texas, Louisiana, and Florida. It is known to occupy areas of Central America, Japan, and India. Chrysomya rufifacies was not discovered in the United States until 1980 and is believed to be a recent immigrant. The fact that this species of fly has only been found in America recently but has been found in most tropic countries of the “Old World
” for some time leads to its surname, the “Old World blow fly”. New research has shown evidence of C. rufifacies in Ontario during the fall season. As temperatures increase due to global warming, colonies of C. rufifacies are predicted to spread well into southern Ontario and Quebec.
Geographical Location
C. megacephala exhibits a widely ranged distribution throughout the Asian regions, South Africa, and South America. This species has recently become well established within the southern United States, as well. C. megacephala is one species that prefers higher temperatures and undergoes the bulk of activity during peak heat periods of the afternoon.
and prey upon other C. rufifacies larvae. Third instar C. rufifacies larvae are capable of potentially expelling other maggots from a feeding site with use of their large fleshy tubercles. The pupae of C. rufifacies typically resemble rodent droppings or cockroach egg casings. The adult C. rufifacies are typically between 10 and 12mm in length with a metallic colored body. The adult fly’s body color is generally a metallic blue/green. While color does play a role in distinguishing between members of the Calliphoridae family, the arrangement of setae is the most accurate way to distinguish most species. All species of Chrysomya possess setae on the meron, and black abdominal tergites. The easiest way to distinguish C. rufifacies from C. megacephala
is to examine the anterior thoracic spiracle, on the adult fly’s body. C. rufifacies has a pale colored anterior thoracic spiracle while C. megacephala has a dark brown or dark orange anterior thoracic spiracle. The C. rufifacies adult possesses three faint thoracic stripes in the pronotal region. C. megacephala are typically a shorter, more stout bodied fly with its tell tale signs being a larger head and prominent red eyes.
. However, C. rufifacies can have the opposite effect since its second and third instar larvae are known to be predacious, feeding on other maggots that might have colonized the body first. In addition, C. rufifacies are known to be cannibalistic as when the second and third instars feed on young first instars. The larvae are able to burrow inches into the ground to reach food and inhabit a buried corpse. It is proven that organic chemistry can be used to determine the age of post-feeding larvae. The hydrocarbon composition of the larvae was found to correlate with age. This is a huge discovery since cuticular hydrocarbon composition is a more accurate method of determining post-feeding larvae age as compared to previous methods of measuring larval crop length, for example.
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
blow fly genus belonging to the family Calliphoridae. The Chrysomya genus contains a number of species including Chrysomya rufifacies
Chrysomya rufifacies
Chrysomya rufifacies is a species belonging to the blow fly family, Calliphoridae, and is most significant in the field of forensic entomology due to its use in establishing or altering postmortem intervals. The common name for the species is the hairy maggot blow fly, and it belongs to the genus...
and Chrysomya megacephala
Chrysomya megacephala
Chrysomya megacephala, more commonly known as the oriental latrine fly, is a warm-weather fly with a greenish-blue metallic box-like body which belongs to the family Calliphoridae . This fly can be a nuisance to humans and even cause accidental myiasis. C...
. The term “Old World blow fly” is a derivative of both the associated family, Calliphoridae (blow flies), 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
Forensic entomology
Forensic entomology is the application and study of insect and other arthropod biology to criminal matters. It is primarily associated with death investigations; however, it may also be used to detect drugs and poisons, determine the location of an incident, and find the presence and time of the...
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.
Adults
Identification traits of the Chrysomya genus include:- 10–12 mm bodies
- Metallic bodies
- Blue/green bodies
- Thick Setae on the meron
- Plumose arista
Keep in mind, however, that not all species will conform completely to these guidelines. Adults feed on many things including decaying matter, excreta, and flowers. In their six week lifespan, (specific length may differ as a result of temperature, weather, etc.) females lay egg masses typically consisting of 50-200 eggs.
Different species within this genus exhibit varying egg laying procedures. The species Chrysomya bezziana
Chrysomya bezziana
Chrysomya bezziana, also known as the Old World screwworm fly or screwworm, is an obligate parasite of mammals. Obligate parasitic flies require a host to complete their development. Named to honor the Italian entomologist Mario Bezzi, this fly is widely distributed in Asia, tropical Africa, India,...
, for example, lay their eggs exclusively on live mammals. In contrast, most Chrysomya species prefer to perform oviposition
Oviposition
Oviposition is the process of laying eggs by oviparous animals.Some arthropods, for example, lay their eggs with an organ called the ovipositor.Fish , amphibians, reptiles, birds and monetremata also lay eggs....
on dead organisms. And, as with many fly genera primary and secondary myiasis
Myiasis
Myiasis is a general term for infection by parasitic fly larvae feeding on the host's necrotic or living tissue. Colloquialisms for myiasis include flystrike, blowfly strike, and fly-blown. In Greek, "myia" means fly....
is possible but unlikely.
Larvae
Chrysomya rufifacies
Chrysomya rufifacies is a species belonging to the blow fly family, Calliphoridae, and is most significant in the field of forensic entomology due to its use in establishing or altering postmortem intervals. The common name for the species is the hairy maggot blow fly, and it belongs to the genus...
, have very distinct thorn-like processes covering its entire body, giving it the common name “hairy maggot blow fly”. The hairy appearance of C. rufifacies makes it easy to distinguish 2nd and 3rd instars from close relative, Chrysomya megacephela. Although the 1st instars are fairly similar, C. megacephela are characterized by thicker spiracle hairs in the 2nd and 3rd instars.
Life cycle
Chrysomya like other fly genera are holometabolous and develop along four stages: egg, larva, pupa, and adult. This short life cycle is extremely important in determining a post mortem interval when studied accurately in medico-criminal entomology. Depending on temperature, the entire life cycle involving development from egg to adult takes from 190 to 598 hours. The pupal stage ranges from 134 hours to 162 hours, and finally the adult emerges around the 237th hour to the 289th hour. Eggs are approximately 1 mm long and are laid in a mass typically consisting of 50 to 200 eggs. If females participate in group ovipositionOviposition
Oviposition is the process of laying eggs by oviparous animals.Some arthropods, for example, lay their eggs with an organ called the ovipositor.Fish , amphibians, reptiles, birds and monetremata also lay eggs....
, the results are much larger masses containing thousands of eggs that may completely cover a decomposing carcass. These eggs are typically yellowish or white in color and, when laid, look like rice balls. The eggs hatch in as little as eight hours. This of course depends on air temperature and the ability of larvae to feed on carrion, until consuming enough calories to progress through the instar stages and pupate. Once this is achieved, third instars travel away from the corpse, usually into shallow soil and pupate. During this time, the larval skin which was initially milky white actually shrinks and hardens to form a dark brown puparium. This stage may last as long as 12 days, while some adults emerge in seven to eight days, again depending on temperature. Generally the warmer the temperature, the faster the life cycle is completed. Once in adult form, C. rufifacies oviposits approximately five days after mating, and lives an average of six weeks.
Myiasis
MyiasisMyiasis
Myiasis is a general term for infection by parasitic fly larvae feeding on the host's necrotic or living tissue. Colloquialisms for myiasis include flystrike, blowfly strike, and fly-blown. In Greek, "myia" means fly....
is the infestation of vertebrate tissue by dipterous
Diptera
Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...
larvae. These larvae feed on the dead or living tissue of their vertebrate hosts. Several species of Chrysomya are known to cause myiasis in animals and/or humans. One species, Chrysomya albiceps, feeds on only diseased tissue of a host. A second species, Chrysomya rufifacies, is a predator of primary parasites and was once used as a treatment for osteomyelitis
Osteomyelitis
Osteomyelitis simply means an infection of the bone or bone marrow...
. Another species, Chrysomya bezziana
Chrysomya bezziana
Chrysomya bezziana, also known as the Old World screwworm fly or screwworm, is an obligate parasite of mammals. Obligate parasitic flies require a host to complete their development. Named to honor the Italian entomologist Mario Bezzi, this fly is widely distributed in Asia, tropical Africa, India,...
, is one of the most important causes of myiasis in the Old World. Cattle are the main host of this larvae, as well as humans and other domestic animals.
Predation
The majority of Chrysomya species are known for being voracious predators of other blow fly species during the maggot stage. Two of the major predatory species of the family Calliphoridae include: Chrysomya rufifacies and C. albiceps. C. albicepsChrysomya albiceps
Chrysomya albiceps is a species belonging to the blow fly family, Calliphoridae. It is of great medical and sanitary importance, being associated with myiasis in Africa and America although it plays a more significant role as a predator of other dipteran larvae...
is thought to be a mechanical vector of various diseases due to its association with filth. C. rufifacies predation of other fly species can have a profound effect on PMI estimates and actual survivorship of the host fly species. Studies showed that predation by C. rufifacies on Cochliomyia macellaria caused a dramatic decrease in survivorship, from 36.3% to 10%.
Chrysomya rufifacies
Geographical LocationChrysomya rufifacies is found widespread throughout the southern US, including southern California, Arizona, Texas, Louisiana, and Florida. It is known to occupy areas of Central America, Japan, and India. Chrysomya rufifacies was not discovered in the United States until 1980 and is believed to be a recent immigrant. The fact that this species of fly has only been found in America recently but has been found in most tropic countries of the “Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
” for some time leads to its surname, the “Old World blow fly”. New research has shown evidence of C. rufifacies in Ontario during the fall season. As temperatures increase due to global warming, colonies of C. rufifacies are predicted to spread well into southern Ontario and Quebec.
Chrysomya megacephala
C. megacephala exhibits a widely ranged distribution throughout the Asian regions, South Africa, and South America. This species has recently become well established within the southern United States, as well. C. megacephala is one species that prefers higher temperatures and undergoes the bulk of activity during peak heat periods of the afternoon.
Characteristics
The larvae of Chrysomya rufifacies are the most easily identified stage of the species. The larvae can get up to approximately 14mm in length with a yellow/orange color and have conical fleshy tubercles down the length of their bodies that give these maggots a slightly hairy appearance even though it does not possess any true hairs. The larvae of C. rufifacies are predatory, meaning that they are typically secondary colonists to a fresh corpse and will devour the maggots of the primary colonist species. If resources are especially scarce, the larvae of C. rufifacies may become cannibalisticCannibalism
Cannibalism is the act or practice of humans eating the flesh of other human beings. It is also called anthropophagy...
and prey upon other C. rufifacies larvae. Third instar C. rufifacies larvae are capable of potentially expelling other maggots from a feeding site with use of their large fleshy tubercles. The pupae of C. rufifacies typically resemble rodent droppings or cockroach egg casings. The adult C. rufifacies are typically between 10 and 12mm in length with a metallic colored body. The adult fly’s body color is generally a metallic blue/green. While color does play a role in distinguishing between members of the Calliphoridae family, the arrangement of setae is the most accurate way to distinguish most species. All species of Chrysomya possess setae on the meron, and black abdominal tergites. The easiest way to distinguish C. rufifacies from C. megacephala
Chrysomya megacephala
Chrysomya megacephala, more commonly known as the oriental latrine fly, is a warm-weather fly with a greenish-blue metallic box-like body which belongs to the family Calliphoridae . This fly can be a nuisance to humans and even cause accidental myiasis. C...
is to examine the anterior thoracic spiracle, on the adult fly’s body. C. rufifacies has a pale colored anterior thoracic spiracle while C. megacephala has a dark brown or dark orange anterior thoracic spiracle. The C. rufifacies adult possesses three faint thoracic stripes in the pronotal region. C. megacephala are typically a shorter, more stout bodied fly with its tell tale signs being a larger head and prominent red eyes.
Forensic Importance
Chrysomya rufifacies adults are usually the first to colonize a fresh corpse. In the southern U.S., this can happen within hours, sometimes minutes, of the host's death. This “hairy maggot blow fly” is the most common maggot found on corpses, and its consistent developmental time is extremely helpful when establishing a post mortem intervalPost mortem interval
Post-mortem interval is the time that has elapsed since a person has died. If the time in question is not known, a number of medical/scientific techniques are used to determine it. This also can refer to the stage of decompostion the person is in....
. However, C. rufifacies can have the opposite effect since its second and third instar larvae are known to be predacious, feeding on other maggots that might have colonized the body first. In addition, C. rufifacies are known to be cannibalistic as when the second and third instars feed on young first instars. The larvae are able to burrow inches into the ground to reach food and inhabit a buried corpse. It is proven that organic chemistry can be used to determine the age of post-feeding larvae. The hydrocarbon composition of the larvae was found to correlate with age. This is a huge discovery since cuticular hydrocarbon composition is a more accurate method of determining post-feeding larvae age as compared to previous methods of measuring larval crop length, for example.
Future Research
Future Research on this genus is particularly important due to its forensic importance. In accordance with such forensic importance studies are being done to better understand the life cycles of these flies. The goal is to be able to predict a more accurate time of death/ colonization. A great deal of effort has been devoted to the predacious nature of the larvae and how the genus has achieved competitive success in many areas of the world. Chrysomya species, however, are hard to breed and study in a lab environment, which proves to be a major obstacle for researchers.Conclusion
The genus Chrysomya is of great importance in forensic entomology, but most notably the medico-criminal field. This chief importance is Chrysomya’s use as a means of developing an accurate postmortem interval in criminal investigations. This genus of “Old World blow flies” is most notably characterized by its blue/green metallic adult body, arrangement of setae, spiracle characteristics, and the presence or absence of fleshy tubercles on the larvae.Species
- Chrysomya albicepsChrysomya albicepsChrysomya albiceps is a species belonging to the blow fly family, Calliphoridae. It is of great medical and sanitary importance, being associated with myiasis in Africa and America although it plays a more significant role as a predator of other dipteran larvae...
(WiedemannChristian Rudolph Wilhelm WiedemannChristian Rudolph Wilhelm Wiedemann , was a German physician, historian, naturalist and entomologist...
, 1819) - Chrysomya bezzianaChrysomya bezzianaChrysomya bezziana, also known as the Old World screwworm fly or screwworm, is an obligate parasite of mammals. Obligate parasitic flies require a host to complete their development. Named to honor the Italian entomologist Mario Bezzi, this fly is widely distributed in Asia, tropical Africa, India,...
Villeneuve, 1914 - Chrysomya chloropyga (WiedemannChristian Rudolph Wilhelm WiedemannChristian Rudolph Wilhelm Wiedemann , was a German physician, historian, naturalist and entomologist...
, 1818) - Chrysomya fulvicruris Robineau-DesvoidyJean-Baptiste Robineau-DesvoidyAndré Jean Baptiste Robineau-Desvoidy was a French physician and entomologist specialising in the study of Diptera and to some extent of the Coleoptera .-Achievements:...
, 1830 - Chrysomya inclinata WalkerFrancis Walker (entomologist)Francis Walker was an English entomologist. He was one of the most prolific authors in entomology, and stirred controversy during his later life as his publications resulted in a huge number of junior synonyms....
, 1861 (Synonyms: C. grienieri Rickenbach, 1959, C. roubaudi SéguyEugène SéguyEugène Séguy was a French entomologist who specialised in Diptera. He held a chair of entomology at the Muséum national d'histoire naturelle in Paris from 1956 -1960.Portraits and Number 7, bottom row.-Works:...
, 1926, C. tellinii BezziMario BezziMario Bezzi was an Italian professor of zoology at the University of Turin. He was also Director of the Turin Museum of Natural History...
, 1908) - Chrysomya marginalis (WiedemannChristian Rudolph Wilhelm WiedemannChristian Rudolph Wilhelm Wiedemann , was a German physician, historian, naturalist and entomologist...
, 1830) - Chrysomya megacephalaChrysomya megacephalaChrysomya megacephala, more commonly known as the oriental latrine fly, is a warm-weather fly with a greenish-blue metallic box-like body which belongs to the family Calliphoridae . This fly can be a nuisance to humans and even cause accidental myiasis. C...
(FabriciusJohan Christian FabriciusJohan Christian Fabricius was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others...
, 1794) - Chrysomya obscura BigotJacques-Marie-Frangile BigotJacques Marie Frangile Bigot was a French naturalist and entomologist most noted for his studies of Diptera. Born in Paris, where he lived all his life, though he had a small house in Quincy-sous-Sénart, Essonne.He became a member of the Entomological Society of France in 1844. His first paper...
, 1891 - Chrysomya putoriaChrysomya putoriaChrysomya putoria, an Old World screw-worm fly, or screw-worm for short, is a species of parasitic fly lay larvae in the living tissue of warm-blooded animals....
(WiedemannChristian Rudolph Wilhelm WiedemannChristian Rudolph Wilhelm Wiedemann , was a German physician, historian, naturalist and entomologist...
, 1830) - Chrysomya rufifaciesChrysomya rufifaciesChrysomya rufifacies is a species belonging to the blow fly family, Calliphoridae, and is most significant in the field of forensic entomology due to its use in establishing or altering postmortem intervals. The common name for the species is the hairy maggot blow fly, and it belongs to the genus...
MacquartJustin Pierre Marie MacquartJustin Pierre Marie Macquart was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species.-Early years:...
, 1843 - Chrysomya villeneuviChrysomya villeneuviChrysomya villeneuvi, or Hairy Maggot, is a South East Asian fly species of forensic importance because the Hairy maggots of this species have been collected from human corpses....
Patton, 1922