Green bottle fly
Encyclopedia
The common green bottle fly (Lucilia sericata) is a common blow-fly
found in most areas of the world, and the most well-known of the numerous green bottle fly
species. It is 10–14 mm long, slightly larger than a housefly
, and has brilliant, metallic, blue-green or golden coloration with black markings. It has black bristle-like hair and three cross-grooves on the thorax
. The wings are clear with light brown vein
s, and the legs and antennae
are black. The maggots (larva
e) of the fly are used for maggot therapy
.
and Australia
. It is coastal in its distribution and prefers warm and moist climates. The female will lay her eggs in meat, fish, animal corpses, infected wounds of humans or animals, and excrement. The larvae of this insect feed on most decomposing tissue, but seem to concentrate on the Ovis
genus which cause many problems for sheep farmers. This insect is also typical to most fly species by having three instar
stages, a pre-pupa stage, and a pupa
stage.
. Identification between these requires microscopic examination of two main distinguishing characteristics. As opposed to L. cuprina which has a metallic green femoral joint in the first pair of legs, L. sericata is blue-black. Also, when looking at the occipital setae, L. sericata has 6–8 bristles on each side while L. cuprina have only one.
L. sericata begin their life cycle by laying a mass of eggs in a wounded area, a carcass or corpse, or in necrotic or decaying tissue. The eggs will hatch out in anywhere from 8–10 hours in warm moist weather to three days in cooler weather. L. sericata can have a lifetime reproductive output of 130 to 172 eggs The pale yellow or grayish conical
larva
e, like that of most blowflies, have two posterior spiracles through which respiration
occurs.These larvae are moderately sized ranging from 10 to 14 millimeters long.
The larva feeds on the dead or necrotic tissue anywhere from 3 to 10 days, again, depending on the temperature. During these 4 to 8 days the larva passes through 3 larval instar
s. The larval instars will develop according to the temperature in their environment. The cooler the temperature (16˚C) the first larva instar will take about 53 hours, the second instar will take about 42 hours and the third instar will take about 98 hours to complete that portion of their life cycle. At warmer temperatures (27˚C) the first larva instar will take about 31 hours, the second instar will take about 12 hours, and the third instar will take about 40 hours to complete that specific stage of the life cycle. The third instar larva will then drop off of the host onto soil where it will pupate for 6 to 14 days. However, if the temperature is relatively cold, the pupa can also overwinter in the soil until the soil temperature warms again. After the pupa transforms, the adult will emerge from the soil and also feed on dead or necrotic tissue. Adults usually lay eggs about 2 weeks after they emerge. Their total life cycle ranges from 2 to 3 weeks, but again can be shortened during the summer when they are most active, or lengthened in cooler seasons. L. sericata usually completes 3 or 4 generations each year.
has been heavily studied and its life cycle and habits are well documented. Due to this, the stage of the insect’s development on a corpse is used to calculate a minimum period of colonization, so that it can used to aid in determining the time of death of the victim. The presence or absence of L. sericata can show a lot about the conditions of the corpse. If the insects seem to be on the path of their normal development, it is likely that the corpse has been undisturbed. If however, the insect shows signs of a disturbed life cycle, or if it is absent from a decaying body, this can show signs of post-mortem tampering with the body. Because L. sericata is one of the first insects to colonize a corpse, it is preferred over many other species in determining an approximate time of colonization. Developmental progress is determined with relative accuracy by measuring the length and weight of larval life cycles.
L. sericata is commonly referred to as the "sheep blowfly" since sheep are its primary host. Although it affects mainly sheep, L. sericata is not host-specific.
In northern Europe
, the fly will lay its eggs in sheep wool. The larvae will then migrate down the wool where it will feed directly on the skin surface. This can cause massive lesions and secondary bacterial infections. In the UK, it is estimated that blowfly strike affects 1 million sheep as well as 80% of sheep farms each year. This causes a huge economic impact in these regions. Not only does it cost money to treat infected animals, but also, measures must be taken to control L. sericata.
Since this fly tends to lay its eggs in wool, a simple and effective way to reduce the incidence of infection is to shear ewes regularly. Enacting simple sanitary measures can also reduce blowfly strike. Timely and proper disposal of carcasses and proper removal of feces
can aid in significantly reducing strike. Moving sheep from warm, humid, and sheltered areas to more open areas can also help to reduce blowfly strike, for this eliminates conditions conducive to fly development. Trapping systems such as sticky paper may also be used to control fly numbers. Treating a flock with chemical agents can be costly but can aid greatly in maintaining the resistance of the flock to L. sericata. Plunge dipping in diazinon can directly kill the fly on contact. This method works from 3 to 8 weeks in controlling the fly. An alternate chemical method is a pyrethroid
pour-on, which will last from 6 to 10 weeks depending on the exact type of pyrethroid used. Cryomazine and dicylanil, which are insect growth regulators, are also effective and last from 10 to 16 weeks. Although chemical treatment can be very effective, it is costly, tedious, and takes up valuable time.
removed larvae from the eyes and facial cavities of a human patient. L. sericata has shown promise in three separate clinical approaches. First, larvae have been shown to debride wounds with extremely low probability of myiasis
upon clinical application. Larval secretion
s have been shown to help in tissue regeneration. L. sericata have also been shown to lower bacteremia
levels in patients infected with MRSA. Basically, L. sericata larvae can be used as biosurgery agents in cases where antibiotics and surgery are impractical.
Studies have shown that larval secretions in vitro
have been successful in enhancing fibroblast
migration to wound site, positively impacting wound closure. It is found that larval therapy of L. sericata is highly recommended for the treatment of wounds infected with Gram-positive bacteria, yet is not as effective for wounds that are infected with Gram-negative bacteria. Also, studies shown that bacteria from the genus Vagococcus were resistant to the maggot excreta/secreta. Attempts are currently undergoing to extract or synthesize the chymotrypsin
s found in larval secretions to destroy MRSA without application of the larva itself.
, and the larval applications for maggot therapy. Efforts in the latter are geared toward making medical professionals more familiar to the current techniques. Like many other ectoparasites, L. sericata has a huge economic impact on farmers. Due to this, many studies and research projects have been put in place since the late 1980’s to help farmers reduce the impact of L. sericata.
Blow-fly
Calliphoridae are insects in the Order Diptera, family Calliphoridae...
found in most areas of the world, and the most well-known of the numerous green bottle fly
Green bottle fly
The common green bottle fly is a common blow-fly found in most areas of the world, and the most well-known of the numerous green bottle fly species. It is 10–14 mm long, slightly larger than a housefly, and has brilliant, metallic, blue-green or golden coloration with black markings. It has...
species. It is 10–14 mm long, slightly larger than a housefly
Housefly
The housefly , Musca domestica, is a fly of the suborder Cyclorrhapha...
, and has brilliant, metallic, blue-green or golden coloration with black markings. It has black bristle-like hair and three cross-grooves on the thorax
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
. The wings are clear with light brown vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...
s, and the legs and antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
are black. The maggots (larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e) of the fly are used for maggot therapy
Maggot therapy
Maggot therapy is a type of biotherapy involving the intentional introduction of live, disinfected maggots into the non-healing skin and soft tissue wound of a human or animal for the purpose of cleaning out the...
.
Distribution and behavior
L. sericata is common all over the world, mainly the southern hemisphere, dominating in AfricaAfrica
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. It is coastal in its distribution and prefers warm and moist climates. The female will lay her eggs in meat, fish, animal corpses, infected wounds of humans or animals, and excrement. The larvae of this insect feed on most decomposing tissue, but seem to concentrate on the Ovis
Ovis
Ovis is a genus of mammals, part of the goat-antelope subfamily of the ruminant family Bovidae. Its five or more highly gregarious species are known as sheep...
genus which cause many problems for sheep farmers. This insect is also typical to most fly species by having three instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
stages, a pre-pupa stage, and a pupa
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
stage.
Morphology
The defining characteristic of L. sericata, and most used when identifying the adult fly is the presence of three bristles on the dorsal mesothorax. This body region is located on the middle of the back of the fly. L. sericata is almost identical to its sister species, Lucilia cuprinaLucilia cuprina
The species Lucilia cuprina, formerly named Phaenicia cuprina, is more commonly known as the Australian sheep blowfly. It belongs to the blow-fly family Calliphoridae, and while some authorities combine the blow flies and the flesh flies together into the Metopiidae family, distinguishable...
. Identification between these requires microscopic examination of two main distinguishing characteristics. As opposed to L. cuprina which has a metallic green femoral joint in the first pair of legs, L. sericata is blue-black. Also, when looking at the occipital setae, L. sericata has 6–8 bristles on each side while L. cuprina have only one.
Life cycle
Cone (geometry)
A cone is an n-dimensional geometric shape that tapers smoothly from a base to a point called the apex or vertex. Formally, it is the solid figure formed by the locus of all straight line segments that join the apex to the base...
larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, like that of most blowflies, have two posterior spiracles through which respiration
Respiration (physiology)
'In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...
occurs.These larvae are moderately sized ranging from 10 to 14 millimeters long.
The larva feeds on the dead or necrotic tissue anywhere from 3 to 10 days, again, depending on the temperature. During these 4 to 8 days the larva passes through 3 larval instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
s. The larval instars will develop according to the temperature in their environment. The cooler the temperature (16˚C) the first larva instar will take about 53 hours, the second instar will take about 42 hours and the third instar will take about 98 hours to complete that portion of their life cycle. At warmer temperatures (27˚C) the first larva instar will take about 31 hours, the second instar will take about 12 hours, and the third instar will take about 40 hours to complete that specific stage of the life cycle. The third instar larva will then drop off of the host onto soil where it will pupate for 6 to 14 days. However, if the temperature is relatively cold, the pupa can also overwinter in the soil until the soil temperature warms again. After the pupa transforms, the adult will emerge from the soil and also feed on dead or necrotic tissue. Adults usually lay eggs about 2 weeks after they emerge. Their total life cycle ranges from 2 to 3 weeks, but again can be shortened during the summer when they are most active, or lengthened in cooler seasons. L. sericata usually completes 3 or 4 generations each year.
Forensic importance
L. sericata is an important species to forensic entomologists. Like most Calliphorids, the insectInsect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
has been heavily studied and its life cycle and habits are well documented. Due to this, the stage of the insect’s development on a corpse is used to calculate a minimum period of colonization, so that it can used to aid in determining the time of death of the victim. The presence or absence of L. sericata can show a lot about the conditions of the corpse. If the insects seem to be on the path of their normal development, it is likely that the corpse has been undisturbed. If however, the insect shows signs of a disturbed life cycle, or if it is absent from a decaying body, this can show signs of post-mortem tampering with the body. Because L. sericata is one of the first insects to colonize a corpse, it is preferred over many other species in determining an approximate time of colonization. Developmental progress is determined with relative accuracy by measuring the length and weight of larval life cycles.
Veterinary importance
Many blowflies have an impact in the veterinary sense, and L. sericata is no exception. In places like the UK and AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
L. sericata is commonly referred to as the "sheep blowfly" since sheep are its primary host. Although it affects mainly sheep, L. sericata is not host-specific.
In northern Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, the fly will lay its eggs in sheep wool. The larvae will then migrate down the wool where it will feed directly on the skin surface. This can cause massive lesions and secondary bacterial infections. In the UK, it is estimated that blowfly strike affects 1 million sheep as well as 80% of sheep farms each year. This causes a huge economic impact in these regions. Not only does it cost money to treat infected animals, but also, measures must be taken to control L. sericata.
Since this fly tends to lay its eggs in wool, a simple and effective way to reduce the incidence of infection is to shear ewes regularly. Enacting simple sanitary measures can also reduce blowfly strike. Timely and proper disposal of carcasses and proper removal of feces
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
can aid in significantly reducing strike. Moving sheep from warm, humid, and sheltered areas to more open areas can also help to reduce blowfly strike, for this eliminates conditions conducive to fly development. Trapping systems such as sticky paper may also be used to control fly numbers. Treating a flock with chemical agents can be costly but can aid greatly in maintaining the resistance of the flock to L. sericata. Plunge dipping in diazinon can directly kill the fly on contact. This method works from 3 to 8 weeks in controlling the fly. An alternate chemical method is a pyrethroid
Pyrethroid
A pyrethroid is an organic compound similar to the natural pyrethrins produced by the flowers of pyrethrums . Pyrethroids now constitute a major commercial household insecticides...
pour-on, which will last from 6 to 10 weeks depending on the exact type of pyrethroid used. Cryomazine and dicylanil, which are insect growth regulators, are also effective and last from 10 to 16 weeks. Although chemical treatment can be very effective, it is costly, tedious, and takes up valuable time.
Medical importance
L. sericata has been of medical importance since 1826, when MeigenJohann Wilhelm Meigen
Johann Wilhelm Meigen was a German entomologist famous for his pioneering work on Diptera.-Early years:Meigen was born in Solingen, the fifth of eight children of Johann Clemens Meigen and Sibylla Margaretha Bick. His parents, though not poor, were not wealthy either. The ran a small shop in...
removed larvae from the eyes and facial cavities of a human patient. L. sericata has shown promise in three separate clinical approaches. First, larvae have been shown to debride wounds with extremely low probability of 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....
upon clinical application. Larval secretion
Secretion
Secretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland. In contrast to excretion, the substance may have a certain function, rather than being a waste product...
s have been shown to help in tissue regeneration. L. sericata have also been shown to lower bacteremia
Bacteremia
Bacteremia is the presence of bacteria in the blood. The blood is normally a sterile environment, so the detection of bacteria in the blood is always abnormal....
levels in patients infected with MRSA. Basically, L. sericata larvae can be used as biosurgery agents in cases where antibiotics and surgery are impractical.
Studies have shown that larval secretions in vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...
have been successful in enhancing fibroblast
Fibroblast
A fibroblast is a type of cell that synthesizes the extracellular matrix and collagen, the structural framework for animal tissues, and plays a critical role in wound healing...
migration to wound site, positively impacting wound closure. It is found that larval therapy of L. sericata is highly recommended for the treatment of wounds infected with Gram-positive bacteria, yet is not as effective for wounds that are infected with Gram-negative bacteria. Also, studies shown that bacteria from the genus Vagococcus were resistant to the maggot excreta/secreta. Attempts are currently undergoing to extract or synthesize the chymotrypsin
Chymotrypsin
Chymotrypsin is a digestive enzyme that can perform proteolysis. Chymotrypsin preferentially cleaves peptide amide bonds where the carboxyl side of the amide bond is a tyrosine, tryptophan, or phenylalanine. These amino acids contain an aromatic ring in their sidechain that fits into a...
s found in larval secretions to destroy MRSA without application of the larva itself.
Continuing research
Due to this species' high forensic interest, extensive research on its life cycle has already been conducted. Medically, however, research is ongoing centered on the secretions produced by L. sericata as an agent against MRSA and VRSAVancomycin-resistant Staphylococcus aureus
Vancomycin-resistant Staphylococcus aureus refers to strains of Staphylococcus aureus that have become resistant to the glycopeptide antibiotic vancomycin. With the increase of staphylococcal resistance to methicillin, vancomycin is often a treatment of choice in infections with...
, and the larval applications for maggot therapy. Efforts in the latter are geared toward making medical professionals more familiar to the current techniques. Like many other ectoparasites, L. sericata has a huge economic impact on farmers. Due to this, many studies and research projects have been put in place since the late 1980’s to help farmers reduce the impact of L. sericata.
External links
- http://cirrusimage.com/flies_blow_green.htm Closeup photographs of Lucilia sericata
- Maggot Therapy Project web site at the University of California, Irvine, list of maggot therapy practitioners
- Green Bottle Maggots help cure MRSA patients
- Monaghan, Peter Rx:Maggots, Notes from Academe, The Chronicle of Higher Education, June 1, 2007 (Vol. LIII, No. 39), p. A48.
- Lucilia sericata on the UFUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ IFASInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
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