The Asiloidea comprise a very large superfamily insects 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 advance ...

, the true

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

. It has a

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

, occurring worldwide. It includes the family

Bombyliidae The Bombyliidae are a family of flies, commonly known as bee flies. Some are colloquially known as bomber flies. Adults generally feed on nectar and pollen, some being important pollinators. Larvae are mostly parasitoids of other insects. Over ...

, the bee flies, which are

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

s, and the

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 Insect mouthparts#Hypopharynx, hypopharynx. The name "robber flies" reflects t ...

, the robber flies, which are predators of other insects.

Description

Adult Asiloidea are large and showy flies in terms of general appearance. They can be recognised by the following features: antenna with no more than 4 flagellomeres, leg empodium usually setiform or absent; wing with cell cup elongate and vein CuA2 ending freely on the wing margin or meeting with vein A1 at or near the wing margin. In families Mydidae, Apioceridae, and Asilidae, the head is at least slightly concave between the eyes and the

ocelli A simple eye or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...

, and both sexes are dichoptic (with a clear separation between the eyes). In Therevidae, Apsilocephalidae, and Scenopinidae, the males are usually

holoptic Holoptic refers to one of the ways in which the arthropod eye develops, particularly the eyes of various species of insects. Unlike dichoptic and cycloptic eyes, holoptic eyes meet along the median dorsal line of the head, in many species near ...

(eyes meet at top of head). Known

larvae A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...

of this superfamily have posterior spiracles arising dorsally from the penultimate abdominal segment, making this feature a

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy sh ...

. However, larvae of most asiloids are unknown and this feature appears in other superfamilies as well. Another feature possessed by most asiloids (except Bombyliidae and Hilarimorphidae) is the larval cranium being modified into a hinged metacephalic rod.

Ecology

Adults usually visit flowers to feed, while larvae usually live in a substrate and are predatory. There are exceptions to this rule, such as Bombyliidae (larvae are parasitoids of other insects) and Asilidae (adults are predatory). The greatest diversity of asiloids is in

arid Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability.Perez-Aguilar, L. Y., Plata ...

, sandy habitats.

Distribution

The superfamily as a whole as a cosmopolitan distribution, as do some of its constituent families, such as Scenopinidae and Therevidae. Other families have more restricted distributions. For example, the only species of Evocoidae occurs in

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

Phylogeny

The ancestral lifestyle for asiloid larvae is believed to be parasitoidism, with this being replaced by predation in all families except Bombyliidae. It is not entirely clear that this superfamily is

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

. It is closely related to the Empidoidea and the

Cyclorrhapha Cyclorrhapha is an Taxon#Ranks, unranked taxon within the infraorder (biology), infraorder Muscomorpha. They are called "Cyclorrhapha" ('circular-seamed flies') with reference to the circular aperture through which the adult escapes the puparium. ...

. Within the superfamily, the "therevoid clade" (Apsilocephalidae, Evocoidae, Scenopinidae and Therevidae) forms a monophyletic group, with Evocoidae being the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to Apsilocephalidae and Therevidae sister to Scenopinidae. This clade diverged from other Asiloidea at the end of the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

period (''c''. 150 million years ago), and its two pairs of families diverged from each other at the beginning of the Cretaceous (144 million years ago).

Families

Apioceridae The Apioceridae, or flower-loving flies, are a small (about 150 species) family of flies, all in the single genus ''Apiocera''. They occur mostly in dry, sandy habitats in the deserts of North America, South America, and Australia. Other genera fo ...

– flower-loving flies *

Apsilocephalidae Apsilocephalidae is a family of fly, flies in the superfamily (zoology), superfamily Asiloidea. It was historically treated as a subfamily within Therevidae, but placed in a separate family in 1991, and subsequently recognized as more distantly re ...

* Apystomyiidae *

– robber flies *

– bee flies * Evocoidae *

Hilarimorphidae The Hilarimorphidae or hilarimorphid flies are a Family (biology), family of Fly, Diptera. They are of uncertain placement and may be related to the Acroceridae. Most species are Nearctic realm, Nearctic. Species Genus ''Cretahilarimorpha'' Mys ...

Mydidae The Mydidae (sometimes misspelled as "Mydaidae"), or Mydas flies, are a cosmopolitan family of flies. It is a small family, with about 471 species described. They are generally large in size, including the largest known fly, '' Gauromydas heros'' ...

– mydas flies * Mythicomyiidae *

Scenopinidae The Scenopinidae or window flies are a small (about 400 described species) family of flies (Diptera), distributed worldwide. In buildings, they are often taken at windows, hence the common name window flies. The two species with cosmopolitan dis ...

– window flies *

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 ...

– stiletto flies The Protapioceridae, a family of

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

flies that were native to

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, are also classified in the Asiloidea.

References

{{Taxonbar, from=Q1938830 Diptera superfamilies