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The Asilidae are the robber fly family, also called assassin flies. They are powerfully built, bristly
flies Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
with a short, stout
proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...
enclosing the sharp, sucking
hypopharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struct ...
. The name "robber flies" reflects their notoriously aggressive predatory habits; they feed mainly or exclusively on other insects and, as a rule, they wait in ambush and catch their prey in flight.


Overview

The Asilidae are a family in the order
Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
, the true flies. The common name for members of the family is the robber flies. The Asilidae are
cosmopolitan Cosmopolitan may refer to: Food and drink * Cosmopolitan (cocktail), also known as a "Cosmo" History * Rootless cosmopolitan, a Soviet derogatory epithet during Joseph Stalin's anti-Semitic campaign of 1949–1953 Hotels and resorts * Cosmopoli ...
, with over 7000 described
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
. Latreille was the authority for establishing the family in 1802. The Asilidae, together with
Bombyliidae The Bombyliidae are a family of flies, commonly known as bee flies. Adults generally feed on nectar and pollen, some being important pollinators. Larvae are mostly parasitoids of other insects. Overview The Bombyliidae are a large family of fl ...
and
Therevidae The Therevidae are a family of flies of the superfamily Asiloidea commonly known as stiletto flies. The family contains about 1,600 described species worldwide, most diverse in arid and semiarid regions with sandy soils. The larvae are predators ...
, are the most representative families of the superfamily of
Asiloidea The Asiloidea comprise a very large superfamily insects in the order Diptera, the true flies. It has a cosmopolitan distribution, occurring worldwide. It includes the family Bombyliidae, the bee flies, which are parasitoids, and the Asilidae, ...
and they form one of the most characteristic groups of the lower
Brachycera The Brachycera are a suborder of the order Diptera. It is a major suborder consisting of around 120 families. Their most distinguishing characteristic is reduced antenna segmentation. Description A summary of the main physical characteristics i ...
. Robber flies have stout, spiny legs and three simple eyes (
ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...
) in a characteristic depression on the tops of their head between their two large
compound eye A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which disti ...
s. They also have a usually dense moustache of stiff bristles on the face; this is called the mystax, a term derived from the Greek ''mystakos'' meaning "moustache" or "upper lip". The mystax has been suggested to afford some protection for the head and face when the flies deal with struggling
prey Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...
; various Asilidae prey on formidable species including stinging Hymenoptera, powerful
grasshoppers Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshop ...
,
dragonflies A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threa ...
and even other Asilidae, in fact practically anything of a suitable size. Some Asilidae do, however, specialize in smaller prey, and this is reflected in their more gracile build. In general, the family attacks a very wide range of prey, including other flies,
beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s,
butterflies Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...
and
moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
s, various
bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...
s,
ants Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22,00 ...
,
dragonflies A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threa ...
and
damselflies Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller and have slimmer bodies. Most species fold the wings along ...
,
ichneumon wasp The Ichneumonidae, also known as the ichneumon wasps, Darwin wasps, or ichneumonids, are a family of parasitoid wasps of the insect order Hymenoptera. They are one of the most diverse groups within the Hymenoptera with roughly 25,000 species cur ...
s,
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...
s, and some
spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s. They do so apparently irrespective of any repugnatorial chemicals the prey may have at their disposal. Many Asilidae when attacked in turn do not hesitate to defend themselves with their probosces and may deliver intensely painful bites if handled incautiously. The antennae are short, have three segments, and sometimes bear a bristle-like structure called an arista. Though they are a very characteristic group for such a large family, the Asilidae may easily be confused with the related and less widely known family
Therevidae The Therevidae are a family of flies of the superfamily Asiloidea commonly known as stiletto flies. The family contains about 1,600 described species worldwide, most diverse in arid and semiarid regions with sandy soils. The larvae are predators ...
. Some points of contrast between the families include that the labium in the Therevidae is not a piercing, predatory organ, but ends in two fleshy labella adapted to the sucking of liquid foods. Again, the Therevidae commonly have fluffy
seta In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...
e above the mouthparts, unlike the stiff chaetae comprising the mystax of the Asilidae. Furthermore, in the Asilidae the depression on the
vertex Vertex, vertices or vertexes may refer to: Science and technology Mathematics and computer science *Vertex (geometry), a point where two or more curves, lines, or edges meet *Vertex (computer graphics), a data structure that describes the position ...
between the eyes tends to be more obvious than in the Therevidae. The fly attacks its prey by stabbing it with its short, strong proboscis, injecting the victim with saliva containing neurotoxic and
proteolytic enzymes Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called protease ...
which very rapidly paralyze the victim and soon digest the insides; the fly then sucks the liquefied material through the proboscis. Many Asilidae have long, tapering
abdomens The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
, sometimes with a sword-like
ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...
. Others, for instance ''
Laphria Laphria may refer to: * Laphria (fly), a genus of robber flies * Laphria (festival) Laphria ( Ancient Greek: τὰ Λάφρια) was an ancient Greek religious festival in honour of the goddess Artemis, held every year in Patras. There was a sanct ...
,'' are fat-bodied
bumblebee A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related gener ...
mimics. Female robber flies deposit whitish-colored eggs on low-lying plants and grasses, or in crevices within soil, bark, or wood. Egg-laying habits depend on the species and their specific habitat; most species lay their eggs in masses, which are then covered with a chalky protective coating. After hatching, robber fly larvae generally seem to live in soil, rotting wood, leaf mold, and similar materials, some being predatory and others detrivorous. Larvae are also predacious, feeding on eggs, larvae, or other soft-bodied insects. Robber flies overwinter as larvae and pupate in the soil. Pupae migrate to the soil surface and emerge as adults, often leaving behind their pupal casing. Complete development ranges from one to three years, depending on species and environmental conditions.


Morphology


Adult

Adults are generally medium to large in size, with an average body width of , but with a range of to more than in length. The shape is generally elongated, due to the conformation of the long tapering
abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
, however there are also compact species with broad abdomens. The integument is covered with thick hair, especially on the
head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...
and
thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
and liveries are often showy, with colors ranging from brown to black to grey, sometimes in contrast with other colors such as red and yellow. Frequently they are
aposematic Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences which make the prey difficult to kill and eat, such as toxicity, venom, foul taste or ...
, imitating the livery of Hymenoptera. The head is free and mobile and dichoptic in both sexes and has three
ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...
arranged in a characteristic depression formed by the elevation of the
compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...
. This feature is clearly visible in the front view and is a morphological peculiarity of Asilidae. The
occipital region The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...
has one or more rows of bristles aligned behind the posterior margin of the eye. The facial region has a convex profile with a characteristic dense bundle of bristles, called a "mystax". The mystax helps protect the head and face when the fly encounters prey bent on defense. Other bristles are arranged on the ocellar tubercle. The antennae are of the aristate type, composed typically of five segments but sometimes from three to four, depending on the structure of the stylus. The scape and
pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...
are generally relatively short and hairy; the third segment (or first flagellomere) has an oval or oblong shape, is generally longer than the two basal segments, and bears a stylus generally composed of two segments, of which the basal is very short. In some asilids, the stylus can be monoarticolate or absent. The mouthparts are short and modified for piercing-sucking. They consist of a strongly sclerotized proboscis which includes the labium and
maxillae The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
which form a food canal, the labrum and a piercing organ, the
hypopharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struct ...
. The proboscis is rounded in cross section or laterally or dorsoventrally compressed and is usually stout, and straight and sometimes able to penetrate through the hard integument of Coleoptera. The maxillary palpi are at the base beside the labium, two-segmented in all Dasypogoninae or single segmented in Asilinae and Leptogastrinae. The thorax is robust and compact. Unlike in other lower Brachycera, it bears long bristles (macrochaeta) useful as
taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
characters. Bristles of this type are always present on the
notopleuron The notopleuron (plural notopleura) is a region on an insect thorax. Notopleura are useful in characterizing species, particularly, though not uniquely, in the Order Diptera (the "true flies"). The notopleuron is a thoracic pleurite (a sclerite ...
(notopleural bristles) and, in two series, on mesonotum (dorsocentral, supralar and postalar). Other bristles are present on the metanotum (dorsocentral bristles on the ventral episternum and at the apex of the mesoscutellum. The legs are relatively long and strong, with many macrochaetes performing a raptatorial function. The wings are well developed, often relatively narrow for speedy flight; the
alula The alula , or bastard wing, (plural ''alulae'') is a small projection on the anterior edge of the wing of modern birds and a few non-avian dinosaurs. The word is Latin and means "winglet"; it is the diminutive of ''ala'', meaning "wing". The al ...
is generally well developed, with the exception of the Leptogastrinae and part of Dasypogoninae. The venation is much as in the
Rhagionidae Rhagionidae or snipe flies are a small family of flies. They get their name from the similarity of their often prominent proboscis that looks like the beak of a snipe. Description Rhagionidae are medium-sized to large flies with slender bodies a ...
,
Tabanidae Horse-flies or horseflies are true flies in the family Tabanidae in the insect order Diptera. They are often large and agile in flight, and only the female horseflies bite animals, including humans, to obtain blood. They prefer to fly in s ...
, and Therevidae; the radial R is always four-branched, with R2+3 unbranched. Details of wing venation determine subfamilies and lower taxa. The wings are most often hyaline, but sometimes smoky or dark colored, or partly infuscated in many genera or completely darkened. The abdomen consists of six to eight visible segments preceding the genitalia in males, but the eighth segment is sometimes entirely or partially concealed, and terminal forming the ovipositor. It is long and narrow conical in most species, but wide, dorsoventrally flattened and short in bee mimics. In the Leptogastrinae, the abdomen is extremely long and slender. In some tribes, the male undergoes axial torsion of 180°.


Egg

The egg is hyaline or pigmented and of variable shape from spherical to oval and up to 2 mm in length. The surface is smooth or bears microsculptures, which are generally polygonal and visible only in the electron microscope.


Larva

The
larva A larva (; plural larvae ) 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. The ...
is apodous, cylindrical, and elongated, more or less flattened dorsoventrally and tapered at the cephalic and caudal ends. The colour is white or yellowish. The head is small, rugged, dark-pigmented and hypognathous, the abdomen is composed of eight apparent urites, with the last two often fused and more or less reduced. The respiratory system is amphineustic, with two pairs of spiracles, one thoracic and one abdominal. Also, rudimentary and nonfunctional stigmata occur in other abdominal segments.


Pupa

The pupa is naked, as in the majority of the Orthorrhapha, exarate and therefore able to move.


Biology

The Asilidae are
predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
, in both the juvenile and the adult stages, and feed on small arthropods, mainly insects. Although predatory forms in the adult stage are present in other taxonomic groups of Diptera, the Asilidae are the most representative for the number of species and for uniformity of feeding behavior. They are aggressive to the point of earning the common name, in English, of "robber flies". The combination of high biodiversity and high predatory activity leads to this family playing an important role in the
ecological stability In ecology, an ecosystem is said to possess ecological stability (or equilibrium) if it is capable of returning to its equilibrium state after a perturbation (a capacity known as resilience) or does not experience unexpected large changes in its ...
of entomofauna. The
lifecycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia * Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring *Life-cycle hypothesis ...
takes place in 1–3 years. The postembryonic development consists of four larval stages (
instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...
s) and one pupa. The larvae of the first instar differ from other stages in both ethology and trophic regime. The larvae of most known asilids live in the soil or in the case of some taxonomic groups, in rotting organic material, usually wood and the bark of dead trees. With regards to feeding behavior, most of the literature describes Asilidae larvae as entomophagous, but doubts remain about the real nature of the trophic regime and its mechanisms. The entomophagy of some species had indeed been already hypothesized by some authors of the 19th century, based on the findings of larvae of asilids associated with larvae of other insects, but Melin (1923) asserted that, in reality, predation was occasional and secondary to the plant-based diet. More recent studies have confirmed the entomophagy of some asilids without extending this species' feeding behavior for the whole family. Less certain, however, is the mechanism of entomophagy: in general, the behavior is cited as predation, but for some species may be ectoparasitoids. Musso (1983) described the feeding behavior of the larvae of ''Machimus rusticus'': the larvae of the first instar does not feed on insects, those of the second instar feed on secretions by larvae of beetles (and may cause death), while the larvae of the third and fourth instars actually behave like predators. In short, the feeding behavior of larval asilids can be intermediate between predation and ectoparasitism. Much better known and described in detail is the behavior of adults. In general, predation in adults is concentrated in the hottest hours in open, sunny spaces, while at night, they take refuge in dense vegetation. The Asilidae are excellent flyers, and in most of the family, capture prey in flight. They are often seen stationed to ambush prey at strategic points. This behavior signifies that sight plays an essential role in the detection of prey and their capture. The prey is caught with the tarsi and injected with a paralyzing saliva. The asilid pierces the integument of the prey with the prepharyx (hyopharynx) in preferential points of least resistance such as the eyes, the membranous area of transition between the head and thorax (neck) or between thorax and abdomen, or between the last urotergiti. Puncture is followed by the injection of saliva, whose active components perform two functions: The
neurotoxin Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature ner ...
s cause paralysis of the victim, while proteolytic enzymes lead to the breakup and liquefaction of internal tissues; in a short time, the predator is able to feed by sucking the internal fluids through the alimentary canal. With regards to interspecific trophic relationships, a large number of reports exists on the prey captured by the Asilidae. Lavigne (2003) has developed a database comprising over 13,000 reports. The prey of Asilidi are predominantly represented by other insects, mostly winged, but several cases in which they have attacked spiders have also been reported. Within the insects, orders that include the most frequent prey of asilids include a wide range of families within the
Coleoptera Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
,
Hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...
, other
Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
,
Hemiptera Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, Reduviidae, assassin bugs, Cimex, bed bugs, and shield bugs. ...
, and
Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
; prey belonging to various other orders (
Odonata Odonata is an order of flying insects that includes the dragonflies and damselflies. Members of the group first appeared during the Triassic, though members of their total group, Odonatoptera, first appeared in Late Carboniferous. The two comm ...
,
Neuroptera The insect order Neuroptera, or net-winged insects, includes the lacewings, mantidflies, antlions, and their relatives. The order consists of some 6,000 species. Neuroptera can be grouped together with the Megaloptera and Raphidioptera in th ...
,
Isoptera Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blattode ...
,
Thysanoptera Thrips ( order Thysanoptera) are minute (mostly long or less), slender insects with fringed wings and unique asymmetrical mouthparts. Different thrips species feed mostly on plants by puncturing and sucking up the contents, although a few are ...
,
Blattodea Blattodea is an order of insects that contains cockroaches and termites. Formerly, termites were considered a separate order, Isoptera, but genetic and molecular evidence suggests they evolved from within the cockroach lineage, cladistically ...
, etc.) are also mentioned. With regards to the specificity of the trophic relationship, Wood (1981) mentions some studies in the literature on the subject. Some genera have been found to be monophagic, but more generally the Asilidae are polyphagic with behaviors that vary from stenophagia to euriphagia. However, cases are reported of stenohage asilids, which if necessary, focus their predatory activity against a species when this forms large populations. Other studies have shown that the ratio between the size of the prey and the asilid varies from 1.8:1 to 3.7:1, with an average of 2.6:1. The ratio tends to increase with decreasing size of the predator. Egg-laying takes place, according to the species, with three different behaviors that relate to the structure and the morphology of the abdomen. Females with an undifferentiated ovipositor release eggs randomly and independently from the substrate. In other cases, however, the abdomen bears a differentiated, specialized ovipositor to lay eggs in the soil or sand, or lay them in cavities within plant tissues.


Habitat and ecology

Asilidae generally occur in habitats that are open, sunny, and dry, even arid. They favour open or scattered vegetation, and some species even frequent bare ground. Typical habitats include
savannah A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the Canopy (forest), canopy does not close. The open canopy allows sufficient light to rea ...
,
forest steppe A forest steppe is a temperate-climate ecotone and habitat type composed of grassland interspersed with areas of woodland or forest. Locations Forest steppe primarily occurs in a belt of forest steppes across northern Eurasia from the eastern ...
, open
steppe In physical geography, a steppe () is an ecoregion characterized by grassland plains without trees apart from those near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the temperate grasslands, ...
, semi
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
,
maquis shrubland 220px, Low maquis in Corsica 220px, High ''macchia'' in Sardinia ( , , ) or ( , ; often in Italian; hr, makija; ; ) is a shrubland biome in the Mediterranean region, typically consisting of densely growing evergreen shrubs. Maquis is char ...
, and related shrubland types such as
fynbos Fynbos (; meaning fine plants) is a small belt of natural shrubland or heathland vegetation located in the Western Cape and Eastern Cape provinces of South Africa. This area is predominantly coastal and mountainous, with a Mediterranean clim ...
and
chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...
. Their biodiversity is lower in forested ecosystems, and where asilids do occur in such environments, they tend to concentrate in the glades and margins. In those conditions, the interrupted canopy leaves space for various species of shrubs and herbaceous plants suited to asilid styles of predation. In general, the biology of the Asilidae is still poorly known, but various authors have studied the population distribution in particular regions and ecosystems. They have classified the behavioral patterns in terms of microenvironments, ecological, and trophic factors, showing how different species of Asilidae favour particular habitats suited to particular patterns of reproduction and predation. Specific studies show correlations between the floristic composition and predatory behaviour.


Distribution

Asilidae occur in all zoogeographical regions except Antarctica. In the Northern Hemisphere, some species are even adapted to tundra.
Alpine Alpine may refer to any mountainous region. It may also refer to: Places Europe * Alps, a European mountain range ** Alpine states, which overlap with the European range Australia * Alpine, New South Wales, a Northern Village * Alpine National Pa ...
species occur at altitudes exceeding 4000 meters/13,000 feet. However, the highest levels of biodiversity are in warm climates; tropical or subtropical and arid or semi-arid regions tend to have the greatest variety of species, followed by areas where rainfall is highly seasonal.


Systematics

The Asilidae currently include over 7500 described
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
in about 556
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
. Their taxonomy is still under study in the light of new specimens and cladistic analysis. The 14 accepted subfamilies are: *
Asilinae Asilinae is a large subfamily of flies in the family Asilidae The Asilidae are the robber fly family, also called assassin flies. They are powerfully built, bristly flies with a short, stout proboscis enclosing the sharp, sucking hypopharynx. ...
* Bathypogoninae * Brachyrhopalinae *
Dasypogoninae Dasypogoninae is a subfamily of robber flies in the family Asilidae. There are more than 60 genera and 520 described species in Dasypogoninae. Genera These 62 genera belong to the subfamily Dasypogoninae: *'' Aczelia'' Carrera, 1955 *'' All ...
* Dioctriinae *
Laphriinae Laphriinae is a subfamily of robber fly, robber flies in the family Asilidae. There are more than 110 genera and 1,000 described species in Laphriinae. Larvae of the genus ''Hyperechia'' are known to grow inside the cells of ''Carpenter bee, Xyloc ...
*
Leptogastrinae Leptogastrinae is a subfamily of robber flies in the family Asilidae. There are more than 450 described species in Leptogastrinae. Genera * '' Acronyches'' Williston, 1908 * '' Ammophilomima'' Enderlein, 1914 * ''Apachekolos'' Martin, 1957 * ' ...
* Ommatiinae * Phellinae *
Stenopogoninae Stenopogoninae is a subfamily of robber flies in the family Asilidae. There are more than 70 genera and 740 described species in Stenopogoninae. Genera These 76 genera belong to the subfamily Stenopogoninae: * '' Afroscleropogon'' Londt, 1999 ...
*
Stichopogoninae Stichopogoninae is a subfamily of robber flies in the family Asilidae The Asilidae are the robber fly family, also called assassin flies. They are powerfully built, bristly flies with a short, stout proboscis enclosing the sharp, sucking hypop ...
* Tillobromatinae * Trigonomiminae * Willistonininae The oldest known member of the family is '' Araripogon'' from the Early Cretaceous (
Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...
)
Crato Formation The Crato Formation is a geologic formation of Early Cretaceous ( Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätte (undisturbed fossil accumulation) for palaeontologists. The strata were laid down mostly duri ...
of Brazil.D. Grimaldi. 1990. Insects from the Santana formation, Lower Cretaceous, of Brazil - Chapter 9. Diptera. ''Bulletin of the American Museum of Natural History'' 195:164-183


Phylogeny

Clade showing relationship of Asiloidea


Notable researchers

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
(Linné; 1758), in the 10th edition of ''
Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomen ...
'', erected the genus ''Asilus'', including 11 species, and added four others in the 12th edition (1767). ''
Asilus crabroniformis The hornet robberfly, ''Asilus crabroniformis'', is a species of predatory insect in the family Asilidae. Reaching more than 25 mm in body length, it is one of the largest flies in the United Kingdom.Express and Echo, ''More info needed abo ...
'' (1758) is the type of the genus. The rank of family is credited to
Leach Leach may refer to: * Leach (surname) * Leach, Oklahoma, an unincorporated community, United States * Leach, Tennessee, an unincorporated community, United States * Leach Highway, Western Australia * Leach orchid * Leach phenotype, a mutation in ...
in Samouelle (1819).
Johan Christian Fabricius Johan Christian Fabricius (7 January 1745 – 3 March 1808) was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others. He was a student of Carl Linnaeus, and is cons ...
in five publications dated from 1775 to 1805, erected the genus ''Damalis'' and described 76 exotic and European species. Wiedemann, in publications appearing between 1817 and 1830, described 235 species, many exotic.
Johann Wilhelm Meigen Johann Wilhelm Meigen (3 May 1764 – 11 July 1845) was a German entomologist famous for his pioneering work on Diptera. Life Early years Meigen was born in Solingen, the fifth of eight children of Johann Clemens Meigen and Sibylla Margaretha ...
in an early work of 1803 erected four genera, three of which now represent subfamilies. He also described many species in ''Systematische Beschreibung der bekannten europäischen zweiflügeligen Insekten'' (1800 to 1838). During the rest of the 19th century, significant contributions were made by
Hermann Loew Friedrich Hermann Loew (19 July 1807 – 21 April 1879) was a German entomologist who specialised in the study of Diptera, an order of insects including flies, mosquitoes, gnats and midges. He described many world species and was the first specia ...
in particular. Other prominent authors dealing with the Asilidae during the 19th century included
Pierre-Justin-Marie Macquart Pierre-Justin-Marie Macquart (8 April 1778 – 25 November 1855) was a French entomologist specialising in the study of Diptera. He worked on world species as well as European and described many new species. Biography Early years Macquart was ...
, Francis Walker,
Camillo Rondani Camillo Rondani (21 November 1808 – 17 September 1879) was an Italian entomologist noted for his studies of Diptera. Early life, family and education Camillo Rondani was born in Parma when the city was part of the French Empire Napoleon ...
, and
Jacques-Marie-Frangile Bigot Jacques Marie Frangile Bigot (1818–1893) was a French naturalist and entomologist most noted for his studies of Diptera. Bigot was born in Paris, France, where he lived all his life, though he had a small house in Quincy-sous-Sénart, Essonne. H ...
.


See also

*
List of soldierflies and allies of Great Britain The following is a list of the larger Brachycera recorded in Britain, this includes the soldierflies and their allies. Family Xylophagidae * '' Xylophagus ater'' - common awl-fly * '' Xylophagus cinctus'' - red-belted awl-fly * '' Xylophagus j ...
*
List of Asilidae species This article lists the described fly species of the family Asilidae. There are about 7100 described species worldwide in this family. A B C D E F G H I J K L M N O P Q R S T U V W Y Z References {{DEFAULTSORT:Asili ...
* List of Asilidae genera


References


Further reading

*Geller-Grimm F (2003):
Photographic atlas and identification key to the robber flies of Germany (Diptera: Asilidae)
', CD-ROM, Amphx-Verlag Halle (Saale). * * *


External links



Comprehensive overview by Fritz Geller-Grimm, Torsten Dikow and Robert J. Lavigne

* ttp://www.faunaeur.org/full_results.php?id=10884 West Palaearctic species including Russiabr>Australasian/Oceanian speciesJapan speciesWorld list species
* ttp://bugguide.net/node/view/151 Family Asilidae at Bugguide.netImages
Family Asilidae at EOL
Images
Atlas of German AsilidaeDiptera.info
on the UF / IFAS Featured Creatures Web site
bee killers, ''Mallophora'' spp.
on the UF / IFAS Featured Creatures Web site
Courting-dance of the robber fly (gallery)
Excellent. Includes structure.
Wing venationFamily Asilidae at EOL
Images. Flowers visited by adults. {{Taxonbar, from=Q837089 Brachycera families Articles containing video clips Taxa named by Pierre André Latreille