Louse 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 of developments in phylogenetic research.
Hemiptera is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from 1 mm (0.04 in) to around 15 cm (6 in), and share a common arrangement of piercing-sucking mouthparts. The name "true bugs" is often limited to the suborder Heteroptera.
Homoptera is a suborder of order Hemiptera that is considered by some taxonomists to be paraphyletic, and therefore deprecated (obsolete). It was therefore split into the suborders Sternorrhyncha, Auchenorrhyncha, and Coleorrhyncha. The earlier work was based on nuclear DNA, but more recent phylogenetic analysis using mitochondrial DNA suggest that Homoptera may be a monophyletic group after all, a sister group of Heteroptera. The cause of the disparity in the analyses is suggested to be the long branch attraction effect in phylogenetic analysis, due to rapidly evolving DNA regions.
Thrips are minute, slender insects with fringed wings and unique asymmetrical mouthparts. Entomologists have described approximately 7,700 species. They fly only weakly and their feathery wings are unsuitable for conventional flight; instead, thrips exploit an unusual mechanism, clap and fling, to create lift using an unsteady circulation pattern with transient vortices near the wings.
The Pterygota are a subclass of insects that includes all winged insects and the orders that are secondarily wingless.
The Exopterygota, also known as Hemipterodea, are a superorder of insects of the subclass Pterygota in the infraclass Neoptera, in which the young resemble adults but have externally developing wings. They undergo a modest change between immature and adult, without going through a pupal stage. The nymphs develop gradually into adults through a process of moulting.
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 Psocodea.
A bird louse is any chewing louse of order Phthiraptera which parasitizes warm-blooded animals, especially birds. Bird lice may feed on feathers, skin, or blood. They have no wings, and their biting mouth parts distinguish them from true lice, which suck blood.
Insect mandibles are a pair of appendages near the insect's mouth, and the most anterior of the three pairs of oral appendages. Their function is typically to grasp, crush, or cut the insect's food, or to defend against predators or rivals. Insect mandibles, which appear to be evolutionarily derived from legs, move in the horizontal plane unlike those of vertebrates, which appear to be derived from gill arches and move vertically.
Psocomorpha is a suborder of barklice, booklice, and parasitic lice in the order Psocodea. There are more than 20 families and 5,300 described species in Psocomorpha.
Trogiomorpha is one of the three major suborders of barklice, booklice, and parasitic lice in the order Psocodea, alongside Troctomorpha and Psocomorpha. There are about 8 families and more than 430 described species in Trogiomorpha. Trogiomorpha is widely agreed to be the earliest diverging of the three suborders, and retains the most primitive characteristics.
Troctomorpha is one of the three major suborders of Psocodea (barklice, booklice, and parasitic lice), alongside Psocomorpha and Trogiomorpha. There are more than 30 families and 5,800 described species in Troctomorpha. The order includes parasitic lice, which are most closely related to the booklice family Liposcelididae.
Pachytroctidae is a family of thick barklice in the order Psocodea. There are about 15 genera and at least 90 described species in Pachytroctidae.
Ectopsocidae is a family of Psocodea belonging to the suborder Psocomorpha. The family includes fewer than 200 species, most of them in the genus Ectopsocus.
Homilopscocidea is an infraorder of Psocodea. It is probably a paraphyletic group, still in use for lack of a better solution. There are about 7 families and more than 1,200 described species in Homilopsocidea.
Psocodea is a taxonomic group of insects comprising the bark lice, book lice and parasitic lice. It was formerly considered a superorder, but is now generally considered by entomologists as an order. Despite the greatly differing appearance of parasitic lice (Phthiraptera), they are believed to have evolved from within the former order Psocoptera, which contained the bark lice and book lice, now found to be paraphyletic. They are often regarded as the most primitive of the hemipteroids. Psocodea contains around 11,000 species, divided among four suborders and more than 70 families. They range in size from 1–10 millimetres (0.04–0.4 in) in length.
Epipsocetae is an infraorder of psocids in the order Psocodea. There are about 5 families and more than 480 described species in Epipsocetae.
Permopsocida is an extinct order of insects known from the Early Permian to the Mid-Cretaceous. It is part of Paraneoptera, alongside bark lice, bugs and thrips. Within Paraneoptera it is considered to be closer to the clade containing bugs and thrips rather than bark lice, with an estimated divergence during the Late Carboniferous. The group was first named as a suborder by Robert John Tillyard in 1926, and was raised to a full order by Huang et al. in 2016. It is currently divided up into three families, Psocidiidae which is known from the Permian to Liassic. Permopsocidae which is only known from the Permian, and Archipsyllidae, which is known from the Late Triassic to mid-Cretaceous (Cenomanian). While most members of the group are known from compression fossils, several members of Archipsyllidae are 3 dimensionally preserved in Burmese amber, which has helped clarify the morphology and phylogenetic position of the group. The morphology of the mouthparts suggests that they were capable of suction feeding and chewing, with preserved angiosperm pollen grains in the gut of Psocorrhyncha suggesting that at least some members of the group were pollenivorous.
Condylognatha or Panhemiptera is a monophyletic grouping (superorder) that contains Hemiptera and Thysanoptera (thrips). Condylognatha belongs to Paraneoptera, which include its sister group, lice (Psocodea).
