Milichiidae
Encyclopedia
Milichiidae are a family
of flies
. Most species are very small and dark in colour. Details of their biology have not yet been properly studied, but they are best known as kleptoparasites of predatory invertebrates, and accordingly are commonly known as freeloader flies or jackal flies. However, because of the conditions under which many species breed out, they also are known as filth flies
of flies
in the suborder
Brachycera
. They were at one time included in the family Carnidae
. At one time or another they have been assigned to various superfamilies, including Carnoidea
, Chloropoidea, and Agromyzoidea. As usual for flies of these groups, Milichiidae imagines
are tiny, but their heads are comparatively large, compared to many fly species of the same size, such as those in the family Phoridae.
Milichiidae are small-to-very-small flies, usually 1 to 3 mm in length. Typically they are black or at least dark in colour. In some species, such as Milichiella argyrogaster, the abdomen of the male is silvery on its dorsal surface because of a covering of fine hairs. The eyes of Milichiidae are often red, though this need not be obvious because many species of the flies are small and dusky. Though the proboscis is fairly long in most species, this is not obvious because it commonly is geniculate, having a knee-like fold in the middle that holds it inconspicuously beneath the head when the animal is not feeding. When it is looking for a place to feed on the prey of a spider or the like, the proboscis is extended, giving an impression of licking. The abdomen is short and broad; it may be impressively distended after a large meal.
l stage generally lasts about 2–3 weeks in temperate
climate
s. Larvae primarily feed on rotting vegetable matter or decaying wood or bark and may be reared from manure or decaying plant materials. At least some are coprophagous and feed on human ordure and other detritus, hence the common name "filth flies". At least some species may breed in dead fish and other carrion, a point of possible interest in forensic entomology.
Some species also have been recovered or reared from birds' nests and bat roosts, but reports of parasitism on birds' nestlings by Milichiidae should be interpreted with caution; at one time Milichiidae and Carnidae
were not regarded as separate families, and it is not always clear how many of such reports refer to any species other than those that nowadays are included in the Carnidae and separated from the Milichiidae.
Human commerce has inadvertently spread some species to all continents but Antarctica. Examples include members of the genera Desmometopa and Milichiella.
The adults of some species linger close to invertebrate predators, where they act as kleptoparasites
, feeding on bodily fluids of the prey. This strategy has given rise to a range of common names such as freeloader flies and jackal flies. The nature of the kleptoparasitism that Milichiidae practise is difficult to detect from direct observation; some observers remark that they seem to lick the prey rather than anything else. However, it seems that they get whatever nourishment they can; the accompanying photographs suggest that at least some species penetrate the thinnest cuticle of a bee in a spider's jaws, extracting tissues that enzymes in the venom of the spider have reduced to a fluid state. When extended, the proboscis certainly is long enough for feeding in such a manner.
The "jackal" habit has been widely documented, with many pictures and references to Millichiidae assembling on the prey of spiders (especially Nephilidae
, Oxyopidae, and Thomisidae). They also visit Asilidae
, Reduviidae
, and even Mantodea
. However, a point that is rarely mentioned is that most prey insects do not attract Milichiidae particularly. Instead they seem only to follow the scents exuded by killed prey such as Hemiptera
, Heteroptera
(stink bugs), and Hymenoptera
. This is compatible with the fact that photographs of Milichiidae on prey, almost universally show them on insects that provide such olfactory clues. This would be compatible with the idea that predators that commonly hunt prey that release a dramatic and characteristic olfactory signal, thereby create a niche for suitable kleptoparasites. In at least species that are attracted to prey of Nephilidae
in Florida
, the major attractants released by Heteropteran prey appear to be low-molecular-weight carbonyl compounds, among which trans-2-hexenal and hexanal are prominent. These compounds are not conspicuous among those released by captured honeybees, so other classes of attractants are likely to be significant as well. In general there is suggestive evidence that the kleptoparasitism relies on olfactory clues; for example, some species seem to operate in the dark, and photographs of approaching flies seem to show them flying upwind, which is consistent with scent following.
A notable point is that spiders' meals can have various forms of significance in nature. For one thing, though they may be the most conspicuous of such partakers, the jackal habit is not unique to the Milichiidae, nor do all species in the family necessarily indulge in it, nor for all the same reasons. Certainly careful inspection of photographs of spiders' prey often will show a few specimens from other families of small flies present among the Milichiidae. Examples include Phoridae and Chloropidae
. The high frequency of Milichiidae around prey of particular species however, suggests that they are more highly adapted to such activities than most. However, this impression might be regional; reports on field work suggest that in parts of Florida for example, the predominant kleptoparasites were in the family Cecidomyiidae
. However, dedicated investigation revealed an impressively wide range of visitors, including Ceratopogonidae
and Phoridae. The attraction of the aromas of feeding female spiders, and even of promising sites for female ambushes, also extends to male crab spiders Thomisidae of some species, but in their case the function of the attraction is likely to be reproduction rather than nourishment. Most kleptoparasitic Michiliidae are females, the males presumably having a lower requirement for proteinaceous food; however, as inferred in from the apparent presentation of droplets of food from the probosces of gorged females, it is possible that the presence of females at the spiders' meals might be reason for males to assemble as well.
Another activity observed in some species of Michiliidae, shows them to be serving a function analogous to that of cleaner wrasse
and cleaner shrimp
; they literally scavenge around the chelicerae
and anal openings
of large spiders, such as species of Araneus and Nephila, that cooperatively spread their wet and sticky chelicerae thus allowing the flies to feed actively all over the bases, fangs and mouth
Some Michiliidae act in various roles as kleptoparasites of various ants.
Subfamily Milichiinae
Subfamily Phyllomyzinae
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of flies
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...
. Most species are very small and dark in colour. Details of their biology have not yet been properly studied, but they are best known as kleptoparasites of predatory invertebrates, and accordingly are commonly known as freeloader flies or jackal flies. However, because of the conditions under which many species breed out, they also are known as filth flies
Affinities and appearance
The Milichiidae are a familyFamily (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of flies
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...
in the suborder
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
Brachycera
Brachycera
Brachycera is a suborder of Diptera. It is a major suborder consisting of around 120 families. The most distinguishing characteristic of the suborder is reduced antenna segmentation...
. They were at one time included in the family Carnidae
Carnidae
Carnidae is a family of flies . There are 5 genera, containing about 88 species worldwide....
. At one time or another they have been assigned to various superfamilies, including Carnoidea
Carnoidea
Carnoidea are a superfamily of Acalyptratae flies.-External links:*, Dedicated website...
, Chloropoidea, and Agromyzoidea. As usual for flies of these groups, Milichiidae imagines
Imago
In biology, the imago is the last stage of development of an insect, after the last ecdysis of an incomplete metamorphosis, or after emergence from the pupa where the metamorphosis is complete...
are tiny, but their heads are comparatively large, compared to many fly species of the same size, such as those in the family Phoridae.
Milichiidae are small-to-very-small flies, usually 1 to 3 mm in length. Typically they are black or at least dark in colour. In some species, such as Milichiella argyrogaster, the abdomen of the male is silvery on its dorsal surface because of a covering of fine hairs. The eyes of Milichiidae are often red, though this need not be obvious because many species of the flies are small and dusky. Though the proboscis is fairly long in most species, this is not obvious because it commonly is geniculate, having a knee-like fold in the middle that holds it inconspicuously beneath the head when the animal is not feeding. When it is looking for a place to feed on the prey of a spider or the like, the proboscis is extended, giving an impression of licking. The abdomen is short and broad; it may be impressively distended after a large meal.
Biology
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...
l stage generally lasts about 2–3 weeks in temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
s. Larvae primarily feed on rotting vegetable matter or decaying wood or bark and may be reared from manure or decaying plant materials. At least some are coprophagous and feed on human ordure and other detritus, hence the common name "filth flies". At least some species may breed in dead fish and other carrion, a point of possible interest in forensic entomology.
Some species also have been recovered or reared from birds' nests and bat roosts, but reports of parasitism on birds' nestlings by Milichiidae should be interpreted with caution; at one time Milichiidae and Carnidae
Carnidae
Carnidae is a family of flies . There are 5 genera, containing about 88 species worldwide....
were not regarded as separate families, and it is not always clear how many of such reports refer to any species other than those that nowadays are included in the Carnidae and separated from the Milichiidae.
Human commerce has inadvertently spread some species to all continents but Antarctica. Examples include members of the genera Desmometopa and Milichiella.
The adults of some species linger close to invertebrate predators, where they act as kleptoparasites
Kleptoparasitism
Kleptoparasitism or cleptoparasitism is a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food...
, feeding on bodily fluids of the prey. This strategy has given rise to a range of common names such as freeloader flies and jackal flies. The nature of the kleptoparasitism that Milichiidae practise is difficult to detect from direct observation; some observers remark that they seem to lick the prey rather than anything else. However, it seems that they get whatever nourishment they can; the accompanying photographs suggest that at least some species penetrate the thinnest cuticle of a bee in a spider's jaws, extracting tissues that enzymes in the venom of the spider have reduced to a fluid state. When extended, the proboscis certainly is long enough for feeding in such a manner.
The "jackal" habit has been widely documented, with many pictures and references to Millichiidae assembling on the prey of spiders (especially Nephilidae
Nephilidae
The Nephilidae are a spider family with 75 described species in four genera. They were formerly grouped in the families Araneidae and Tetragnathidae. The genus Singafrotypa was moved to Araneidae in 2002.All nephilid genera partially renew their webs....
, Oxyopidae, and Thomisidae). They also visit Asilidae
Asilidae
Insects in the Diptera family Asilidae are commonly called robber flies. The family Asilidae contains about 7,100 described species worldwide....
, Reduviidae
Reduviidae
Reduviidae is a large, cosmopolitan family of predatory insects in the suborder Heteroptera...
, and even Mantodea
Mantis
Mantis is the common name of any insect in the order Mantodea, also commonly known as praying mantises. The word itself means "prophet" in Latin and Greek...
. However, a point that is rarely mentioned is that most prey insects do not attract Milichiidae particularly. Instead they seem only to follow the scents exuded by killed prey such as Hemiptera
Hemiptera
Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...
, Heteroptera
Heteroptera
Heteroptera is a group of about 40,000 species of insects in the Hemiptera. Sometimes called "true bugs", that name more commonly refers to Hemiptera as a whole, and "typical bugs" might be used as a more unequivocal alternative since among the Hemiptera the heteropterans are most consistently and...
(stink bugs), and Hymenoptera
Hymenoptera
Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
. This is compatible with the fact that photographs of Milichiidae on prey, almost universally show them on insects that provide such olfactory clues. This would be compatible with the idea that predators that commonly hunt prey that release a dramatic and characteristic olfactory signal, thereby create a niche for suitable kleptoparasites. In at least species that are attracted to prey of Nephilidae
Nephilidae
The Nephilidae are a spider family with 75 described species in four genera. They were formerly grouped in the families Araneidae and Tetragnathidae. The genus Singafrotypa was moved to Araneidae in 2002.All nephilid genera partially renew their webs....
in Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, the major attractants released by Heteropteran prey appear to be low-molecular-weight carbonyl compounds, among which trans-2-hexenal and hexanal are prominent. These compounds are not conspicuous among those released by captured honeybees, so other classes of attractants are likely to be significant as well. In general there is suggestive evidence that the kleptoparasitism relies on olfactory clues; for example, some species seem to operate in the dark, and photographs of approaching flies seem to show them flying upwind, which is consistent with scent following.
A notable point is that spiders' meals can have various forms of significance in nature. For one thing, though they may be the most conspicuous of such partakers, the jackal habit is not unique to the Milichiidae, nor do all species in the family necessarily indulge in it, nor for all the same reasons. Certainly careful inspection of photographs of spiders' prey often will show a few specimens from other families of small flies present among the Milichiidae. Examples include Phoridae and Chloropidae
Chloropidae
Chloropidae is a family of flies commonly known as frit flies or grass flies. There are approximately 2000 described species in over 160 genera distributed worldwide. These are usually very small flies, yellow or black and appearing shiny due to the virtual absence of any hairs. The majority of the...
. The high frequency of Milichiidae around prey of particular species however, suggests that they are more highly adapted to such activities than most. However, this impression might be regional; reports on field work suggest that in parts of Florida for example, the predominant kleptoparasites were in the family Cecidomyiidae
Cecidomyiidae
Cecidomyiidae is a family of flies known as gall midges or gall gnats. As the name implies, the larvae of most gall midges feed within plant tissue, creating abnormal plant growths called galls.These are very fragile small insects usually only 2–3 mm in length and many are less than...
. However, dedicated investigation revealed an impressively wide range of visitors, including Ceratopogonidae
Ceratopogonidae
Ceratopogonidae, or biting midges , are a family of small flies in the order Diptera...
and Phoridae. The attraction of the aromas of feeding female spiders, and even of promising sites for female ambushes, also extends to male crab spiders Thomisidae of some species, but in their case the function of the attraction is likely to be reproduction rather than nourishment. Most kleptoparasitic Michiliidae are females, the males presumably having a lower requirement for proteinaceous food; however, as inferred in from the apparent presentation of droplets of food from the probosces of gorged females, it is possible that the presence of females at the spiders' meals might be reason for males to assemble as well.
Another activity observed in some species of Michiliidae, shows them to be serving a function analogous to that of cleaner wrasse
Wrasse
The wrasses are a family, Labridae, of marine fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 82 genera, which are divided into nine subgroups or tribes....
and cleaner shrimp
Cleaner shrimp
Cleaner shrimp is a generic term for any swimming decapod crustacean that cleans other organisms of parasites. This is a widely-cited example of symbiosis: a relationship in which both parties benefit. The fish benefit by having parasites removed from them, and the shrimp gain the nutritional value...
; they literally scavenge around the chelicerae
Chelicerae
The chelicerae are mouthparts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata , and Pycnogonida . Chelicerae are pointed appendages which are used to grasp food, and are found in place of the chewing mandibles most other arthropods have...
and anal openings
Anus
The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...
of large spiders, such as species of Araneus and Nephila, that cooperatively spread their wet and sticky chelicerae thus allowing the flies to feed actively all over the bases, fangs and mouth
Some Michiliidae act in various roles as kleptoparasites of various ants.
Selected genera
Subfamily Madizinae- Aldrichiomyza HendelFriedrich Georg HendelFriedrich Georg Hendel was an Austrian Hauptsschuldirektor and entomologist mainly interested in Diptera. He described very many new species and made important contributions to the higher taxonomy of the Diptera.He was born in Vienna and died in Baden bei Wien...
, 1914 - Desmometopa LoewHermann LoewFriedrich Hermann Loew was a German entomologist who specialised in the study of Diptera, an order of insects including flies, mosquitoes, gnats and midges...
, 1866 - Enigmilichia Deeming, 1981
- Leptometopa BeckerTheodor BeckerTheodor Becker was a German civil engineer and entomologist primarily known for his work with flies....
, 1903 - Madiza FallénCarl Fredrik FallénCarl Fredrik Fallén was a Swedish botanist and entomologist.Fallén taught at the Lund University. He wrote Diptera Sueciae .In 1817, Fallen discovered the Muscina stabulans species of flies....
, 1810 - Paramyia Williston, 1897
- Stomosis MelanderAxel Leonard MelanderAxel Leonard Melander was an American entomologist specialising in Diptera and Hymenoptera.His collection is shared between the German Entomological Institute and the Smithsonian Institution Washington D.C-External links:*...
, 1913
Subfamily Milichiinae
- Eusiphona CoquillettDaniel William CoquillettDaniel William Coquillett was an American entomologist who specialised in Diptera. He wrote Revision of the dipterous family Therevidae...
, 1897 - Milichia MeigenJohann Wilhelm MeigenJohann 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...
, 1830 - Milichiella Giglio-Tos, 1895
- Pholeomyia Bilimek, 1867
- Ulia BeckerTheodor BeckerTheodor Becker was a German civil engineer and entomologist primarily known for his work with flies....
, 1907
Subfamily Phyllomyzinae
- Borneomyia Brake, 2004
- Costalima Sabrosky, 1953
- Microsimus Aldrich, 1926
- Neophyllomyza MelanderAxel Leonard MelanderAxel Leonard Melander was an American entomologist specialising in Diptera and Hymenoptera.His collection is shared between the German Entomological Institute and the Smithsonian Institution Washington D.C-External links:*...
, 1913 - Paramyioides Papp, 2001
- Phyllomyza FallénCarl Fredrik FallénCarl Fredrik Fallén was a Swedish botanist and entomologist.Fallén taught at the Lund University. He wrote Diptera Sueciae .In 1817, Fallen discovered the Muscina stabulans species of flies....
, 1810 - Genus Xenophyllomyza Ozerov, 1992