Lucilia illustris
Encyclopedia
Lucilia illustris is a member of the Calliphoridae family of flies commonly known as a blow fly. Along with several other species, L. illustris is commonly referred to as the green bottle fly
. L. illustris is typically 6–9 mm in length and has a metallic blue-green thorax
. The larva
e 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.
Due to the predictable nature of development, Lucilia illustris is often used by forensic entomologist
s to determine time and place of death. Medically, L. illustris is often used for Maggot Debridement Therapy because it only causes myiasis
in necrotic tissue. Lucilia illustris was first described by the German entolomogist Johann Wilhelm Meigen
in 1826. Its specific epithet is derived from the Latin illustris 'brilliant'.
A metallic blue-green thorax
reflects bronze and purple. In some lights, silvery pollen appears on its back, as well as a dark line that extends along the back. Black setae can be found on both the propleuron and the hypopleuron, with brown setae on the prosternum. There are dark brown or black sclerite
s located at the wing-base, as well as dark brown or black found on the spiracle
. L. illustris has black legs, translucent wings, and does not have a costal
spine.
The abdomen
has similar coloring to the thorax, but looks slightly white in certain lights. The first segment of the abdomen has metallic and dark brown coloring. The second segment has a slight indication of a spot in the middle of the back on the front margin, as well as a row of hardly apparent bristles along the margin. The third and fourth segments both have long upright bristles, but the fourth segment's hairs are scattered and also includes a marginal row of bristles.
e develop in three stages, or instar
s. In the first instar, it is difficult to determine the dispersion of the spines due to some segments not being pigmented. The second through ninth segments each have a full set of spines as anterior borders. However, the color starts to change in the eighth and ninth segments: segment 8 has lighter colored spines and the ninth segment's spines are practically void of color. The spines are reduced to one or two rows in segment 9, but segment 10 has several rows that are lightly colored. Segment 11 is characterized by two or three rows of dark spines as a posterior border on the dorsal side. Segment 12 is characterized by tubercles, with an inner set on the upper border. Cephalopharyngeal sclerite are darkly pigmented.
In the second instar, segments 2 through 9 are characterized by a complete band of spines as a front border (as in the first instar). Segment 8 has spines, but they are only located ventrally and laterally. Segments 9 through 12 have complete bands of spines as a posterior border, but segment 9 only has one or two irregular rows of spines. The tubercle
s found on the upper border of the last segment are have a broad curve and are similar in size to the third instar tubercles. The cephaloskeleton has a dorsal cornua of consistent width until it comes to a point at the posterior end. Six to eight branches are found on the frontal spiracles.
The third instar has bands of spines completely around the spine at segments 2 through 9. Segment 10 has a band of spines, but there is generally a small area on the front that is not complete. There are five or six irregular rows on the back of segment 11. Segment 12 is usually smooth on its dorsal surface. The posterior spiracles are relatively large and darkly pigmented; the anterior spiracles (generally six to eight) have relatively large branches. The cephaloskeleton is also large and darkly colored.
s. However, the female also needs a protein
source to mature her eggs and become sexually responsive. Mating will commonly take place in close range of where the eggs will be deposited. The species' sex ratio is generally equal, but around an egg laying vector, the females can be found in masses. Approximately 200 eggs will be laid in a single batch of an adult female, and each individual female can lay up to 10 batches in her three-week life span. Eggs will primarily be found on a carcass, but can also occasionally be in open wounds or excrement. Temperature is a crucial factor in the development time of the blow fly and this particular species. At 25 degrees Celsius
, the eggs will take about 24 hours to hatch.
Upon hatching, Lucilia illustris enters its larval stages of development, commonly called a maggot
. As in other green bottle fly
species, their larvae are carrion
feeders and will generally infest any decomposing corpse. Larvae go through three separate developmental stages called instar
s. Lucilia illustris typically prefers cooler weather, and when ambient temperatures are around 7.7 degrees Celsius, L. illustris will usually be the largest group of maggots on a corpse. Between each instar
, the Lucilia illustris larvae will molt. The current instar of the larvae can be determined by examining the respiratory organs, called spiracle
s. If the maggot mass is successfully identified, tissue loss from the corpse can also be used to determine which instar the larvae are in.
After the third instar is complete, the larvae will go underground and pupa
te. In ideal conditions, an adult Lucilia illustris fly will emerge from the pupa on an average of 10 days. The adult form of Lucilia illustris attracts rapidly to carrion
. Lucilia illustris larvae can reach the third instar in as few as fourteen days from the time of death.
For example, the body of a young, white female was found on a roadside in the northeastern part of the United States. Cause of death was a single shotgun blast to the right side of the head. While processing the crime scene, samples of blow fly adults and maggots were taken from the wound. Upon review, entomologists determined the woman had been killed about five days prior to her discovery and that the body had been placed in that location close to the time of death based upon the samples recovered at the scene. Further investigation revealed the woman’s boyfriend as the prime suspect. He was later found hanged in a motel with a suicide note that stated he committed the homicide five days prior in the location the body was discovered.
is the infestation of flesh of living animals by arthropod
s. Lucilia illustris has been implicated as a myiasis
agent in sheep in northerly Palaearctic regions. L. illustris is also capable of infesting other wildlife and domesticated livestock which, along with sheep infestations, poses a potential economic problem. L. illustris is a facultative myiasis agent, which means that it does not depend on infestation of living animals to survive. It primarily feeds on necrotic tissue when attacking living hosts, which is thought to be part of the reason myiasis evolved as an extension of the normal feeding behavior of L. illustris.
at levels high enough to cause sickness and even death in pheasants. L. illustris can cause outbreaks of C. botulinum in avian production practices by spreading the bacteria from previously infected carrion to live pheasants. Dispersal from the infected carrion by third instar larvae to pupate can spread the bacteria into other pens of animals. As little as one gram of infected maggot mass has been shown to contain 5.2 times pheasant which is enough toxin to kill several pheasant. More than 5000 larvae have been known to colonize a single carcass which is theoretically enough maggots to completely infect a moderately sized game pheasant practice with C. botulinum.
The effect of blowflies on birds is a current research issue. Species such as meadowlarks, sparrows and finches suffer from blowflies. The blowfly larvae infest the nests, sucking the blood of the nestlings injuring and possibly killing them. Current research on bird blow flies include the study of new species of blow flies, the effect on the hosts and the distribution of the blow flies toward each species.
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...
. L. illustris is typically 6–9 mm in length and has a metallic blue-green thorax
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
. The 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 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
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
protein in order to breed and lay eggs.
Due to the predictable nature of development, Lucilia illustris is often used by forensic entomologist
Forensic entomologist
Forensic entomologists are those involved in the branch of entomology that involves insects and violent crime or the law, known as forensic entomology. This includes three main branches: medicocriminal entomology, urban entomology, and stored product entomology...
s to determine time and place of death. Medically, L. illustris is often used for Maggot Debridement Therapy because it only causes 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....
in necrotic tissue. Lucilia illustris was first described by the German entolomogist Johann Wilhelm Meigen
Johann 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...
in 1826. Its specific epithet is derived from the Latin illustris 'brilliant'.
Description
Lucilia illustris is 6–9 mm in length. Its bucca (cheeks) are colored black with slightly gray pollinose and black hairs. The first segment of the antenna is black; the second generally orange-tipped, and the third segment is about three times the length of the second segment and colored a dark brown or black. The arista (a bristle on the antenna) is dark brown or black, and has cilia that are dark and long. The back of its head is black and there are three to four rows of black cilia behind the eyes.A metallic blue-green thorax
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
reflects bronze and purple. In some lights, silvery pollen appears on its back, as well as a dark line that extends along the back. Black setae can be found on both the propleuron and the hypopleuron, with brown setae on the prosternum. There are dark brown or black sclerite
Sclerite
A sclerite is a hardened body part. The term is used in various branches of biology for various structures including hardened portions of sponges, but it is most commonly used for the hardened portions of arthropod exoskeletons....
s located at the wing-base, as well as dark brown or black found on the spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
. L. illustris has black legs, translucent wings, and does not have a costal
Costal
Costal may refer to:* an adjective related to the rib in anatomy** Costal cartilage, a type of cartilage forming bars which serve to prolong the ribs forward** Costal facet...
spine.
The abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
has similar coloring to the thorax, but looks slightly white in certain lights. The first segment of the abdomen has metallic and dark brown coloring. The second segment has a slight indication of a spot in the middle of the back on the front margin, as well as a row of hardly apparent bristles along the margin. The third and fourth segments both have long upright bristles, but the fourth segment's hairs are scattered and also includes a marginal row of bristles.
Larvae
The larvaLarva
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 develop in three stages, or 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. In the first instar, it is difficult to determine the dispersion of the spines due to some segments not being pigmented. The second through ninth segments each have a full set of spines as anterior borders. However, the color starts to change in the eighth and ninth segments: segment 8 has lighter colored spines and the ninth segment's spines are practically void of color. The spines are reduced to one or two rows in segment 9, but segment 10 has several rows that are lightly colored. Segment 11 is characterized by two or three rows of dark spines as a posterior border on the dorsal side. Segment 12 is characterized by tubercles, with an inner set on the upper border. Cephalopharyngeal sclerite are darkly pigmented.
In the second instar, segments 2 through 9 are characterized by a complete band of spines as a front border (as in the first instar). Segment 8 has spines, but they are only located ventrally and laterally. Segments 9 through 12 have complete bands of spines as a posterior border, but segment 9 only has one or two irregular rows of spines. The tubercle
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....
s found on the upper border of the last segment are have a broad curve and are similar in size to the third instar tubercles. The cephaloskeleton has a dorsal cornua of consistent width until it comes to a point at the posterior end. Six to eight branches are found on the frontal spiracles.
The third instar has bands of spines completely around the spine at segments 2 through 9. Segment 10 has a band of spines, but there is generally a small area on the front that is not complete. There are five or six irregular rows on the back of segment 11. Segment 12 is usually smooth on its dorsal surface. The posterior spiracles are relatively large and darkly pigmented; the anterior spiracles (generally six to eight) have relatively large branches. The cephaloskeleton is also large and darkly colored.
Behavior
Adults of Lucilia illustris feed on flowering plantFlowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s. However, the female also needs a protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
source to mature her eggs and become sexually responsive. Mating will commonly take place in close range of where the eggs will be deposited. The species' sex ratio is generally equal, but around an egg laying vector, the females can be found in masses. Approximately 200 eggs will be laid in a single batch of an adult female, and each individual female can lay up to 10 batches in her three-week life span. Eggs will primarily be found on a carcass, but can also occasionally be in open wounds or excrement. Temperature is a crucial factor in the development time of the blow fly and this particular species. At 25 degrees Celsius
Celsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
, the eggs will take about 24 hours to hatch.
Upon hatching, Lucilia illustris enters its larval stages of development, commonly called a maggot
Maggot
In everyday speech the word maggot means the larva of a fly ; it is applied in particular to the larvae of Brachyceran flies, such as houseflies, cheese flies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and Crane flies...
. As in other 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, their larvae are carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
feeders and will generally infest any decomposing corpse. Larvae go through three separate developmental stages called 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. Lucilia illustris typically prefers cooler weather, and when ambient temperatures are around 7.7 degrees Celsius, L. illustris will usually be the largest group of maggots on a corpse. Between each 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...
, the Lucilia illustris larvae will molt. The current instar of the larvae can be determined by examining the respiratory organs, called spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s. If the maggot mass is successfully identified, tissue loss from the corpse can also be used to determine which instar the larvae are in.
After the third instar is complete, the larvae will go underground and 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...
te. In ideal conditions, an adult Lucilia illustris fly will emerge from the pupa on an average of 10 days. The adult form of Lucilia illustris attracts rapidly to carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
. Lucilia illustris larvae can reach the third instar in as few as fourteen days from the time of death.
Forensic importance
Blow flies typically are the first to arrive when blood or body fluid is present. Hence, blow flies are the primary means of estimating a time of death in case work. The life cycle from egg to maggot to adult has been researched thoroughly; therefore, the estimation from egg to adult is accurate within simply a few hours based upon temperature and climate during previous days. This estimation is crucial when determining a time of death to further an investigation. Specifically, Lucilia illustris is found on carrion located in sunlight or otherwise bright areas.For example, the body of a young, white female was found on a roadside in the northeastern part of the United States. Cause of death was a single shotgun blast to the right side of the head. While processing the crime scene, samples of blow fly adults and maggots were taken from the wound. Upon review, entomologists determined the woman had been killed about five days prior to her discovery and that the body had been placed in that location close to the time of death based upon the samples recovered at the scene. Further investigation revealed the woman’s boyfriend as the prime suspect. He was later found hanged in a motel with a suicide note that stated he committed the homicide five days prior in the location the body was discovered.
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 flesh of living animals by arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s. Lucilia illustris has been implicated as a 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....
agent in sheep in northerly Palaearctic regions. L. illustris is also capable of infesting other wildlife and domesticated livestock which, along with sheep infestations, poses a potential economic problem. L. illustris is a facultative myiasis agent, which means that it does not depend on infestation of living animals to survive. It primarily feeds on necrotic tissue when attacking living hosts, which is thought to be part of the reason myiasis evolved as an extension of the normal feeding behavior of L. illustris.
Vector of disease causing agents
Lucilia illustris larvae have been shown to be a mechanical vector of Clostridium botulinumClostridium botulinum
Clostridium botulinum is a Gram-positive, rod-shaped bacterium that produces several toxins. The best known are its neurotoxins, subdivided in types A-G, that cause the flaccid muscular paralysis seen in botulism. It is also the main paralytic agent in botox. C. botulinum is an anaerobic...
at levels high enough to cause sickness and even death in pheasants. L. illustris can cause outbreaks of C. botulinum in avian production practices by spreading the bacteria from previously infected carrion to live pheasants. Dispersal from the infected carrion by third instar larvae to pupate can spread the bacteria into other pens of animals. As little as one gram of infected maggot mass has been shown to contain 5.2 times pheasant which is enough toxin to kill several pheasant. More than 5000 larvae have been known to colonize a single carcass which is theoretically enough maggots to completely infect a moderately sized game pheasant practice with C. botulinum.
Current research
Recent research involving blow flies ranges from maggot therapy to identifying different species of bird blow flies. Maggot Debridement Therapy (MDT) uses specially selected fly larvae for the cleansing of non-healing wounds. Gangrenous wounds are examples of non-healing wounds that can clinically be treated more effectively by MDT than more common treatments. “Medicinal maggots have three actions: 1) they debride (clean) wounds by dissolving the dead (necrotic), infected tissue; 2) they disinfect the wound, by killing bacteria; and 3) they stimulate wound healing.” According to the Federal Drug Administration, medicinal maggots are the first live organisms to be marketed in the United States.The effect of blowflies on birds is a current research issue. Species such as meadowlarks, sparrows and finches suffer from blowflies. The blowfly larvae infest the nests, sucking the blood of the nestlings injuring and possibly killing them. Current research on bird blow flies include the study of new species of blow flies, the effect on the hosts and the distribution of the blow flies toward each species.