The Asiloidea comprise a very large superfamily insects in the order Diptera, the true

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 m ...

. It has a cosmopolitan distribution, occurring worldwide. It includes the family

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 ...

, the bee flies, which are parasitoids, 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 hypopharynx. The name "robber flies" reflects their notoriously aggressive pre ...

, 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 (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 ...

, 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 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 character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to hav ...

. 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 A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ...

, 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 the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

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. It is closely related to the

Empidoidea The Empidoidea are a large monophyletic superfamily of true flies, the sister taxon to the Muscomorpha (Cyclorrhapha). These two groups are sometimes united in the unranked taxon Eremoneura. There are some 10,000 known species within Empidoidea, ...

and the

Cyclorrhapha Cyclorrhapha is an unranked taxon within the infraorder Muscomorpha. They are called "Cyclorrhapha" ('circular-seamed flies') with reference to the circular aperture through which the adult escapes the puparium. This is a circumscriptional name t ...

. Within the superfamily, the "therevoid clade" (Apsilocephalidae, Evocoidae, Scenopinidae and Therevidae) forms a monophyletic group, with Evocoidae being the sister group to Apsilocephalidae and Therevidae sister to Scenopinidae. This clade diverged from other Asiloidea at the end of the

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

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 ...

– flower-loving flies * Apsilocephalidae * Apystomyiidae *

– robber flies *

– bee flies * Evocoidae * Hilarimorphidae * Mydidae – mydas flies *

Mythicomyiidae Mythicomyiidae, commonly called mythicomyiids, are very tiny flies (0.5–5.0 mm) found throughout most parts of the world, especially desert and semi-desert regions, except the highest altitudes and latitudes. They are not as common in the t ...

* Scenopinidae – 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 predator ...

– stiletto flies The Protapioceridae, a family of extinct flies that were native to China, are also classified in the Asiloidea.

References

{{Taxonbar, from=Q1938830 Diptera superfamilies