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

. 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 ...

, the bee flies, which are parasitoids, and the Asilidae, 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-le ...

, and both sexes are dichoptic (with a clear separation between the eyes). In Therevidae, Apsilocephalidae, and Scenopinidae, the males are usually holoptic (eyes meet at top of head). Known

larvae 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. T ...

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 eas ...

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 cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

. It is closely related to the 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 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 Mya. The J ...

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 – flower-loving flies * Apsilocephalidae * Apystomyiidae * Asilidae – robber flies *

– bee flies * Evocoidae * Hilarimorphidae *

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 – window flies * Therevidae – 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