The Pterygota ( grc, πτερυγωτός, pterugōtós, winged) are a subclass of

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s that includes the winged insects. It also includes insect orders that are secondarily wingless (that is, insect groups whose ancestors once had wings but that have lost them as a result of subsequent evolution). The pterygotan group comprises almost all insects. The

orders not included are the

Archaeognatha The Archaeognatha are an order of apterygotes, known by various common names such as jumping bristletails. Among extant insect taxa they are some of the most evolutionarily primitive; they appeared in the Middle Devonian period at about the ...

(jumping bristletails) and the

Zygentoma Zygentoma are an order in the class Insecta, and consist of about 550 known species. The Zygentoma include the so-called silverfish or fishmoths, and the firebrats. A conspicuous feature of the order are the three long caudal filaments. The t ...

(

silverfish The silverfish (''Lepisma saccharinum'') is a species of small, primitive, wingless insect in the order Zygentoma (formerly Thysanura). Its common name derives from the insect's silvery light grey colour, combined with the fish-like appearance ...

es and

firebrat The firebrat (''Thermobia domestica'') is a small hexapod (typically 1–1.5 cm), in the order Zygentoma. Habitat Firebrats prefer higher temperatures and require some humidity, and can be found in bakeries and near boilers or f ...

s), two primitively wingless insect orders. Also not included is

Entognatha The Entognatha are a class of wingless and ametabolous arthropods, which, together with the insects, makes up the subphylum Hexapoda. Their mouthparts are entognathous, meaning that they are retracted within the head, unlike the insects. Entog ...

, which consist of three orders no longer considered to be insects:

Protura The Protura, or proturans, and sometimes nicknamed coneheads, are very small (0.6-1.5mm long), soil-dwelling animals, so inconspicuous they were not noticed until the 20th century. The Protura constitute an order of hexapods that were previously ...

Collembola Springtails (Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura). Although the three orders are sometimes grouped together in a class called Ento ...

, and

Diplura The order Diplura ("two-pronged bristletails") is one of three orders of non-insect hexapods within the class Entognatha (alongside Collembola (springtails) and Protura). The name "diplura", or "two tails", refers to the characteristic pair of ...

Systematics

Traditionally, this group was divided into the

infraclass In biological classification, class ( la, classis) is a taxonomic rank, as well as a taxonomic unit, a taxon, in that rank. It is a group of related taxonomic orders. Other well-known ranks in descending order of size are life, domain, kingdo ...

Paleoptera The name Palaeoptera (from Greek ( 'old') + ( 'wing')) has been traditionally applied to those ancestral groups of winged insects (most of them extinct) that lacked the ability to fold the wings back over the abdomen as characterizes the Neopte ...

and

Neoptera Neoptera (Ancient Greek ''néos'' (“new”) + ''pterón'' (“wing”)) is a classification group that includes most orders of the winged insects, specifically those that can flex their wings over their abdomens. This is in contrast with the mo ...

. The former are nowadays strongly suspected of being

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

, and better treatments (such as dividing or dissolving the group) are presently being discussed. In addition, it is not clear how exactly the neopterans are related among each other. The

Exopterygota The Exopterygota (Ancient Greek ''ἔξω'' (éxō, “outside”) + ''πτερόν'' (pterón, “wing”) + New Latin ''-ota'' (“having”)), also known as Hemipterodea, are a superorder of insects of the subclass Pterygota in the infracla ...

might be a similar assemblage of rather ancient

hemimetabolous Hemimetabolism or hemimetaboly, also called incomplete metamorphosis and paurometabolism,McGavin, George C. ''Essential Entomology: An Order-by-Order Introduction''. Oxford: Oxford University Press, 2001. pp. 20. is the mode of development of certa ...

insects among the Neoptera like the Palaeoptera are among insects as a whole. The

holometabolous Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphic trait of all insects in the superorder Endopterygot ...

Endopterygota Endopterygota (from Ancient Greek ''endon'' 'inner' + ''pterón'' 'wing' + New Latin ''-ota'' 'having'), also known as Holometabola, is a superorder of insects within the infraclass Neoptera that go through distinctive larval, pupal, and adult s ...

seem to be very close relatives, indeed, but nonetheless appear to contain several

clades A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, t ...

of related orders, the status of which is not agreed upon. The following scheme uses finer divisions than the one above, which is not well-suited to correctly accommodating the fossil groups.

Infraclass Palaeoptera

(probably paraphyletic) * Ephemeroptera (mayflies) *

Palaeodictyoptera The Palaeodictyoptera are an extinct order of medium-sized to very large, primitive Palaeozoic paleopterous insects. They are informative about the evolution of wings in insects. Overview They were characterized by beak-like mouthparts, used ...

†(extinct) *

Megasecoptera Megasecoptera is a Paleozoic insect order. There are 22 known families of megasecopterans, with about 35 known genera. Overview Like all other paleodictyopteroids, the megasecopterans had sucking mouthparts. The suctorial mouth parts were proba ...

†(extinct) *

Archodonata Archodonata is an extinct order of palaeozoic paleopterous insects, sometimes included in Odonata Odonata is an order of flying insects that includes the dragonflies and damselflies. Members of the group first appeared during the Triassic, th ...

†(extinct) *

Diaphanopterodea The Diaphanopterodea or Paramegasecoptera are an extinct order of moderate to large-sized Palaeozoic insects. They are first known from the Middle Carboniferous (late Serpukhovian or early Bashkirian in age), and include some of the earliest know ...

†(extinct) *

Protodonata Meganisoptera is an extinct order of very large to gigantic insects, informally called griffinflies. The order was formerly named Protodonata, the "proto-Odonata", for their similar appearance and supposed relation to modern Odonata (damselflies ...

Meganisoptera Meganisoptera is an extinct order of very large to gigantic insects, informally called griffinflies. The order was formerly named Protodonata, the "proto-Odonata", for their similar appearance and supposed relation to modern Odonata (damselflies ...

†(extinct; sometimes included in Odonata) *

Protanisoptera The Odonatoptera are a superorder (sometimes treated as an order) of ancient winged insects, placed in the probably paraphyletic group Palaeoptera. The dragonflies and damselflies are the only living members of this group, which was far more div ...

†(extinct; sometimes included in Odonata) *

Triadophlebioptera The Odonatoptera are a superorder (sometimes treated as an order) of ancient winged insects, placed in the probably paraphyletic group Palaeoptera. The dragonflies and damselflies are the only living members of this group, which was far more ...

†(extinct; sometimes included in Odonata) *

Protozygoptera The Odonatoptera are a superorder (sometimes treated as an order) of ancient winged insects, placed in the probably paraphyletic group Palaeoptera. The dragonflies and damselflies are the only living members of this group, which was far more ...

or Archizygoptera †(extinct; sometimes included in Odonata) *

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 ...

(

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 ...

)

Infraclass Neoptera

Superorder

Caloneurodea Caloneurodea is an extinct order of polyneopteran neopteran insects in the superorder Orthopterida. The Caloneurodea are known from fossils found in North America, Europe, Russia, and Asia and had a palegeographic range confined to Laurussia. F ...

†(extinct) *

Titanoptera Titanoptera is an extinct order of neopteran insects from late Carboniferous to Triassic periods. Titanopterans were very large in comparison with modern insects, some having wingspans of up to or even . Description Titanopterans are related ...

†(extinct) *

Protorthoptera The Protorthoptera are an extinct order of Palaeozoic insects, and represent a wastebasket taxon and paraphyletic assemblage of basal neoptera. They appear during the Middle Carboniferous (late Serpukhovian or early Bashkirian), making them a ...

†(extinct) * Plecoptera (stoneflies) *

Embioptera The order (biology), order Embioptera, commonly known as webspinners or footspinners, are a small group of mostly Tropics, tropical and Subtropics, subtropical insects, classified under the Subclass (biology), subclass Pterygota. The order has ...

(webspinners) *

Zoraptera The insect order (biology), order Zoraptera, commonly known as angel insects, contains small and soft bodied insects with two forms: winged with wings sheddable as in termites, dark and with eyes (compound) and ocelli (simple); or wingless, pale ...

(angel insects) *

Dermaptera Earwigs make up the insect order Dermaptera. With about 2,000 species in 12 families, they are one of the smaller insect orders. Earwigs have characteristic cerci, a pair of forcep-like pincers on their abdomen, and membranous wings folded ...

(earwigs) *

Orthoptera Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – grassho ...

(

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, etc.) * Phasmatodea (stick insects – tentatively placed here) *

Notoptera The wingless insect order Notoptera, a group first proposed in 1915, had been largely unrecognized since its original conception, until resurrected in 2004. As now defined, the order comprises five families, three of them known only from fossils ...

(gladiators and ice-crawlers – tentatively placed here) *Proposed superorder

Dictyoptera Dictyoptera (from Greek δίκτυον ''diktyon'' "net" and πτερόν ''pteron'' "wing") is an insect superorder that includes two extant orders of polyneopterous insects: the order Blattodea (termites and cockroaches together) and the o ...

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 ...

(cockroaches and termites) **

Mantodea Mantises are an order (Mantodea) of insects that contains over 2,400 species in about 460 genera in 33 families. The largest family is the Mantidae ("mantids"). Mantises are distributed worldwide in temperate and tropical habitats. They ha ...

(mantids) **

Alienoptera Alienopteridae is an extinct family of dictyopterans, known from the Mid-Cretaceous to Eocene. They are noted for their unusual combination of features not found in other dictyopterans. Taxonomy It was originally assigned to its own order Alie ...

†(extinct) *Proposed superorder

Paraneoptera Paraneoptera or Acercaria is a superorder of insects which includes lice ( bark lice and true lice), thrips, and hemipterans, the true bugs. It also includes the extinct order Permopsocida, known from fossils dating from the Early Permian to t ...

Psocoptera Psocoptera are a paraphyletic group of insects that are commonly known as booklice, barklice or barkflies. The name Psocoptera has been replaced with Psocodea in recent literature, with the inclusion of the former order Phthiraptera into Psocode ...

(booklice, barklice) **

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 ...

(thrips) **

Phthiraptera Louse ( : lice) is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a result o ...

(

lice Louse ( : lice) is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a result o ...

) **

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. ...

(true bugs) Superorder

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 ...

(

ant 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 ...

s, bees, etc.) *

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 ...

(beetles) *

Strepsiptera The Strepsiptera are an order of insects with eleven extant families that include about 600 described species. They are endoparasites in other insects, such as bees, wasps, leafhoppers, silverfish, and cockroaches. Females of most species never ...

(twisted-winged parasites) *

Raphidioptera Snakeflies are a group of predatory insects comprising the order Raphidioptera with two extant families: Raphidiidae and Inocelliidae, consisting of roughly 260 species. In the past, the group had a much wider distribution than it does now; sn ...

(snakeflies) * Megaloptera ( alderflies, etc.) * Neuroptera (net-veined insects) *Proposed superorder Mecopteroidea/

Antliophora Panorpida or Mecopterida is a proposed superorder of Endopterygota. The conjectured monophyly of the Panorpida is historically based on morphological evidence, namely the reduction or loss of the ovipositor and several internal characteristics, i ...

Mecoptera Mecoptera (from the Greek: ''mecos'' = "long", ''ptera'' = "wings") is an order of insects in the superorder Endopterygota with about six hundred species in nine families worldwide. Mecopterans are sometimes called scorpionflies after their lar ...

(scorpionflies, etc.) **

Siphonaptera Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, ar ...

(

flea Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, a ...

s) **

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 ...

(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 ...

) ** Protodiptera †(extinct) *Proposed superorder

Amphiesmenoptera Amphiesmenoptera is an insect superorder, established by S. G. Kiriakoff, but often credited to Willi Hennig in his revision of insect taxonomy for two sister orders: Lepidoptera (butterflies and moths) and Trichoptera (caddisflies). In 2017, a t ...

Trichoptera The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...

(

caddisflies The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...

) **

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 ...

(

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 ...

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) Neoptera orders ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'' * Glosselytrodea †(extinct) *

Miomoptera Miomoptera is an extinct order of insects. Although it is thought to be a common ancestor of all holometabolous insects, because no smooth transition between Miomoptera and other holometabolous insect orders is known, it is considered to be in a ...

†(extinct)

References

External links

{{Authority control Insect taxonomy Arthropod subclasses Extant Pennsylvanian first appearances Dicondylia