Psocoptera
Encyclopedia
Psocoptera are an order
of insect
s that are commonly known as booklice, barklice or barkflies. They first appeared in the Permian
period, 295–248 million years ago. They are often regarded as the most primitive of the hemipteroid
s. Their name originates from the Greek
word psokos meaning gnawed or rubbed and ptera meaning wings
. There are more than 5,500 species in 41 families in three suborders. Many of these species have only been described in recent years.
They range in size from 1–10 millimeters (0.04–0.4 in) in length.
The species known as booklice received their common name because they are commonly found amongst old book
s—they feed upon the paste used in binding
. The barklice are found harmlessly on trees, feeding on algae and lichen
. No member of this order is currently considered endangered
; in fact, in 2007, Atlantopsocus adustus, a species native to Madeira and the Canary Islands, was found to have colonized the mild Cornish coast
of southwest England.
s, and the central lobe of the maxilla
is modified into a slender rod. This rod is used to brace the insect while it scrapes up detritus with its mandibles. They also have a swollen forehead, large compound eyes, and three ocelli. Some species can spin silk from glands in their mouth.
The forewings are up to 1.5 times as long as the hindwings, and all four wings have a relatively simple venation pattern, with few cross-veins. The legs are slender and adapted for walking, rather than gripping, as in the true lice. The abdomen has nine segments, and no cerci
.
There is often considerable variation in the appearance of individuals within the same species. Many have no wings or ocelli, and may have a different shape to the thorax. Other, more subtle, variations are also known, such as changes to the development of the seta
e. The significance of such changes is uncertain, but their function appears to be different from similar variations in, for example, aphid
s. Like aphids, however, many psocids are parthenogenic, and the presence of males may even vary between different races of the same species.
Psocids lay their eggs in minute crevices or on foliage, although a few species are known to be viviparous. The young are born as miniature, wingless versions of the adult. These nymph
s typically molt six times before reaching full adulthood. The total lifespan of a psocid is rarely more than a few months.
Booklice are wingless and range from approximately 1mm to 2mm in length (1/25" to 1/13"). They are easily mistaken for bedbug nymphs and vice-versa. Booklouse eggs take 2 to 4 weeks to hatch and can reach adulthood approximately 2 months later. Adult booklice can live for six months. Besides damaging books, they also sometimes infest food storage areas, where they feed on dry, starchy materials. They are scavengers and do not bite humans.
with many segments (22–50 antennomeres) and always three-segmented tarsi.
Trogiomorpha is the smallest suborder of the Psocoptera sensu stricto (i.e. excluding Phthiraptera), with about 340 species in 7 families, ranging from the monospecific fossil family Archaeotropidae to the speciose Lepidopsocidae (over 200 species).
Trogiomorpha comprises infraorder Atropetae (extant families Lepidopsocidae, Psoquillidae and Trogiidae, and fossil families Archaeotropidae and Empheriidae) and infraorder Psocathropetae (families Psyllipsocidae and Prionoglarididae
).
Troctomorpha comprises the Infraorder Amphientometae (families Amphientomidae
, Compsocidae
, Electrentomidae, Musapsocidae
, Protroctopsocidae and Troctopsocidae
) and Infraorder Nanopsocetae (families Liposcelididae
, Pachytroctidae
and Sphaeropsocidae
). Troctomorpha are now known to also contain the order Phthiraptera (lice), and are therefore paraphyletic, as are Psocoptera as a whole.
Some Troctomorpha, such as Liposcelis (which are similar to lice in morphology), are often found in birds' nests, and it is possible that a similar behavior in the ancestors of lice is at the origin of the parasitism seen today.
Psocomorpha is the largest suborder of the Psocoptera sensu stricto (i.e. excluding Phthiraptera), with about 3,600 species in 24 families, ranging from the species-poor Bryopsocidae (2 spp.) to the speciose Psocidae (about 900 spp).
Psocomorpha comprises Infraorder Epipsocetae (families Cladiopsocidae
, Dolabellopsocidae
, Epipsocidae
, Neurostigmatidae and Ptiloneuridae
), Infraorder Caeciliusetae (families Amphipsocidae
, Asiopsocidae
, Caeciliusidae
, Dasydemellidae
and Stenopsocidae
), Infraorder Homilopsocidea (families Archipsocidae
, Bryopsocidae
, Calopsocidae
, Ectopsocidae
, Elipsocidae
, Lachesillidae
, Mesopsocidae
, Peripsocidae
, Philotarsidae
, Pseudocaeciliidae
and Trichopsocidae
) and Infraorder Psocetae
(families Hemipsocidae
, Myopsocidae
, Psilopsocidae
and Psocidae
).
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s that are commonly known as booklice, barklice or barkflies. They first appeared in the Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
period, 295–248 million years ago. They are often regarded as the most primitive of the hemipteroid
Hemiptera
Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...
s. Their name originates from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
word psokos meaning gnawed or rubbed and ptera meaning wings
Insect wing
Insects are the only group of invertebrates known to have evolved flight. Insects possess some remarkable flight characteristics and abilities, still far superior to attempts by humans to replicate their capabilities. Even our understanding of the aerodynamics of flexible, flapping wings and how...
. There are more than 5,500 species in 41 families in three suborders. Many of these species have only been described in recent years.
They range in size from 1–10 millimeters (0.04–0.4 in) in length.
The species known as booklice received their common name because they are commonly found amongst old book
Book
A book is a set or collection of written, printed, illustrated, or blank sheets, made of hot lava, paper, parchment, or other materials, usually fastened together to hinge at one side. A single sheet within a book is called a leaf or leaflet, and each side of a leaf is called a page...
s—they feed upon the paste used in binding
Bookbinding
Bookbinding is the process of physically assembling a book from a number of folded or unfolded sheets of paper or other material. It usually involves attaching covers to the resulting text-block.-Origins of the book:...
. The barklice are found harmlessly on trees, feeding on algae and lichen
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
. No member of this order is currently considered endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
; in fact, in 2007, Atlantopsocus adustus, a species native to Madeira and the Canary Islands, was found to have colonized the mild Cornish coast
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...
of southwest England.
Anatomy and biology
Psocids are small, scavenging insects with a relatively generalized body plan. They feed primarily on fungi, algae, lichen, and organic detritus. They have chewing mandibleMandible (arthropod)
thumb|250px|The mandibles of a [[Bull ant]]The mandible of an arthropod is either of a pair of mouthparts used for biting, cutting and holding food. Mandibles are often simply referred to as jaws. Mandibles are present in the extant subphyla Myriapoda , Crustacea and Hexapoda...
s, and the central lobe of the maxilla
Insect mouthparts
Insects exhibit a range of mouthparts, adapted to particular modes of feeding. The earliest insects had chewing mouthparts...
is modified into a slender rod. This rod is used to brace the insect while it scrapes up detritus with its mandibles. They also have a swollen forehead, large compound eyes, and three ocelli. Some species can spin silk from glands in their mouth.
The forewings are up to 1.5 times as long as the hindwings, and all four wings have a relatively simple venation pattern, with few cross-veins. The legs are slender and adapted for walking, rather than gripping, as in the true lice. The abdomen has nine segments, and no cerci
Cercus
Cerci are paired appendages on the rear-most segments of many arthropods, including insects and arachnids but not crustaceans. Cerci often serve as sensory organs, but they may also be used as weapons or copulation aids, or they may simply be vestigial structures.Typical cerci may appear to be...
.
There is often considerable variation in the appearance of individuals within the same species. Many have no wings or ocelli, and may have a different shape to the thorax. Other, more subtle, variations are also known, such as changes to the development of the seta
Seta
Seta is a biological term derived from the Latin word for "bristle". It refers to a number of different bristle- or hair-like structures on living organisms.-Animal setae:In zoology, most "setae" occur in invertebrates....
e. The significance of such changes is uncertain, but their function appears to be different from similar variations in, for example, aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...
s. Like aphids, however, many psocids are parthenogenic, and the presence of males may even vary between different races of the same species.
Psocids lay their eggs in minute crevices or on foliage, although a few species are known to be viviparous. The young are born as miniature, wingless versions of the adult. These nymph
Nymph (biology)
In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...
s typically molt six times before reaching full adulthood. The total lifespan of a psocid is rarely more than a few months.
Booklice are wingless and range from approximately 1mm to 2mm in length (1/25" to 1/13"). They are easily mistaken for bedbug nymphs and vice-versa. Booklouse eggs take 2 to 4 weeks to hatch and can reach adulthood approximately 2 months later. Adult booklice can live for six months. Besides damaging books, they also sometimes infest food storage areas, where they feed on dry, starchy materials. They are scavengers and do not bite humans.
Suborder Trogiomorpha
Trogiomorpha have antennaeAntenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
with many segments (22–50 antennomeres) and always three-segmented tarsi.
Trogiomorpha is the smallest suborder of the Psocoptera sensu stricto (i.e. excluding Phthiraptera), with about 340 species in 7 families, ranging from the monospecific fossil family Archaeotropidae to the speciose Lepidopsocidae (over 200 species).
Trogiomorpha comprises infraorder Atropetae (extant families Lepidopsocidae, Psoquillidae and Trogiidae, and fossil families Archaeotropidae and Empheriidae) and infraorder Psocathropetae (families Psyllipsocidae and Prionoglarididae
Prionoglarididae
Prionoglarididae is a family of Psocoptera that are characterised by the reduction or simplification of the lacinia in adults and the specialised form of the male genitalia....
).
Suborder Troctomorpha
Troctomorpha have antennae with 15–17 segments and two-segmented tarsi.Troctomorpha comprises the Infraorder Amphientometae (families Amphientomidae
Amphientomidae
Amphientomidae is a family of Psocoptera belonging to the suborder Troctomorpha. The presence of scales on their wings gives them a superficial resemblance to the unrelated family Lepidopsocidae and both families can pass for microlepidoptera to the untrained eye. The family comprises 100 species...
, Compsocidae
Compsocidae
Compsocidae is a family of Psocoptera belonging to the suborder Troctomorpha. The family comprises two extant species in two genera, found in Central America.-Sources:...
, Electrentomidae, Musapsocidae
Musapsocidae
Musapsocidae is a family of Psocoptera belonging to the suborder Troctomorpha. The pterostigma in their fore-wing has the characteristic of not being closed proximally. The family comprises 2 genera.-Sources:...
, Protroctopsocidae and Troctopsocidae
Troctopsocidae
In the insect world, troctopsocidae is a family of Psocoptera belonging to the suborder Troctomorpha. The family consists of six genera.-Sources:...
) and Infraorder Nanopsocetae (families Liposcelididae
Liposcelididae
Liposcelididae is a family of barklice belonging to the suborder Troctomorpha. Members of this family are small and flattened, and often wingless....
, Pachytroctidae
Pachytroctidae
Pachytroctidae is a family of Psocoptera belonging to the suborder Troctomorpha. Members of this family are small, often macropterous, with a distinct wing-venation. The family comprises less than 100 species arranged in ten genera.-Sources:...
and Sphaeropsocidae
Sphaeropsocidae
In the insect world, Sphaeropsocidae is a family of Psocoptera belonging to the suborder Troctomorpha. Members of this family have reduced, coriaceous wings. The family comprises 22 known species in eight genera.-Sources:...
). Troctomorpha are now known to also contain the order Phthiraptera (lice), and are therefore paraphyletic, as are Psocoptera as a whole.
Some Troctomorpha, such as Liposcelis (which are similar to lice in morphology), are often found in birds' nests, and it is possible that a similar behavior in the ancestors of lice is at the origin of the parasitism seen today.
Suborder Psocomorpha
Psocomorpha are notable for having antennae with 13 segments. They have two- or three-segmented tarsi, this condition being constant (e.g. Psocidae) or variable (e.g. Pseudocaeciliidae) within families. Their wing venation is variable, the most common type being that found in the genus Caecilius (rounded, free areola postica, thickened, free pterostigma, r+s two-branched, m three-branched). Additional veins are found in some families and genera (Dicropsocus and Goja in Epipsocidae, many Calopsocidae, etc.)Psocomorpha is the largest suborder of the Psocoptera sensu stricto (i.e. excluding Phthiraptera), with about 3,600 species in 24 families, ranging from the species-poor Bryopsocidae (2 spp.) to the speciose Psocidae (about 900 spp).
Psocomorpha comprises Infraorder Epipsocetae (families Cladiopsocidae
Cladiopsocidae
Cladiopsocidae is a family of Psocoptera belonging to the suborder Psocomorpha. Like the other members of the infra-order Epipsocetae, they have a labrum with two sclerotized ridges.-Sources:...
, Dolabellopsocidae
Dolabellopsocidae
Dolabellopsocidae is a family of Psocoptera belonging to the suborder Psocomorpha, that includes, among others, the genus Isthmopsocus. Like the other members of the infra-order Epipsocetae, they have a labrum with two sclerotized ridges.-Sources:...
, Epipsocidae
Epipsocidae
Epipsocidae is a family of Psocoptera belonging to the suborder Psocomorpha, that includes, among others, the genera Epipsocus, Epipsocopsis, and the New Guinean endemic Dicropsocus. The only European species in the family is the apterous Bertkauia lucifuga...
, Neurostigmatidae and Ptiloneuridae
Ptiloneuridae
Ptiloneuridae is a family of Psocoptera belonging to the suborder Psocomorpha. Like the other members of the infra-order Epipsocetae, they have a labrum with two sclerotized ridges.-Sources:...
), Infraorder Caeciliusetae (families Amphipsocidae
Amphipsocidae
Amphipsocidae is a family of Psocoptera belonging to the suborder Psocomorpha. Like the other members of the infra-order Caeciliusetae, they have a broad, flat labrum, with well defined edges. The family is composed of 170 species arranged in 17 genera....
, Asiopsocidae
Asiopsocidae
Asiopsocidae is a family of Psocoptera belonging to the infraorder Caeciliusetae. The family is composed of 14 known species in three genera.-Sources:...
, Caeciliusidae
Caeciliusidae
Caeciliusidae is a family of Psocoptera belonging to the suborder Psocomorpha. The family was once named Caeciliidae, but the latter name was changed because of homonymy with a family of amphibians.-Sources:...
, Dasydemellidae
Dasydemellidae
In the insect world, Dasydemellidae is a family of Psocoptera belonging to the suborder Psocomorpha, in the infraorder Caeciliusetae. The family is composed of about 30 species.-Sources:...
and Stenopsocidae
Stenopsocidae
Stenopsocidae is a family of Psocoptera belonging to the suborder Psocomorpha, in the infraorder Caeciliusetae. Member of this family have an areola postica connected to the M vein by a crossvein. The family is composed of about 100 species.-Sources:...
), Infraorder Homilopsocidea (families Archipsocidae
Archipsocidae
Archipsocidae is a family of Psocoptera belonging to the suborder Psocomorpha. Members of the family are characterised by their reduced wing venation. Some species are viviparous. The family includes about 80 species in five genera.-Sources:...
, Bryopsocidae
Bryopsocidae
Bryopsocidae is a family of Psocoptera belonging to the suborder Psocomorpha. The family includes 2 species from New Zealand.-Sources:*Lienhard, C. & Smithers, C. N. 2002. Psocoptera : World Catalogue and Bibliography. Instrumenta Biodiversitatis, vol. 5. Muséum d'histoire naturelle, Genève....
, Calopsocidae
Calopsocidae
Calopsocidae is a family of Psocoptera belonging to the suborder Psocomorpha. Members of the family often have a Reticulation reticulate venation and coriaceous wings, and a head with a sharp vertex. Calopsocidae are especially diverse in New Guinea. This family is closely related to...
, Ectopsocidae
Ectopsocidae
Ectopsocidae is a family of Psocoptera belonging to the suborder Psocomorpha. Members of the family are characterised by their absence of an areola postica in their wings, like in the family Peripsocidae...
, Elipsocidae
Elipsocidae
Elipsocidae is a family of Psocoptera belonging to the suborder Homilopsocidea. Member of the family have a free areola postica. Many species are apterous. The family includes about 130 species in 26 genera.-Sources:...
, Lachesillidae
Lachesillidae
Lachesillidae is a family of Psocoptera belonging to the suborder Psocomorpha. Members of the family are characterised by a rounded, free areola postica in their wings. Males have diverse sclerotized genitalic structures. The family includes close to 300 species, most of them in the genus...
, Mesopsocidae
Mesopsocidae
Mesopsocidae is a family of Psocoptera belonging to the suborder Psocomorpha. Members of the family are characterised by their free areola postica. The family includes more than 70 species.-Sources:...
, Peripsocidae
Peripsocidae
Peripsocidae is a family of Psocoptera belonging to the suborder Psocomorpha. Members of the family are characterised by their absence of an areola postica in their wings. Many of the recently described genera are closely allied to Peripsocus, and only two genera are presented here. The family...
, Philotarsidae
Philotarsidae
Philotarsidae is a family of Psocoptera belonging to the suborder Psocomorpha. The family is closely related to the families Pseudocaeciliidae and Calopsocidae.-Sources:...
, Pseudocaeciliidae
Pseudocaeciliidae
Pseudocaeciliidae is a family of Psocoptera belonging to the suborder Psocomorpha. The name stems from a superficial resemblance to the distantly related family Caeciliusidae . The family is closely related to the families Philotarsidae and Calopsocidae.-Sources:*Lienhard, C. & Smithers, C. N....
and Trichopsocidae
Trichopsocidae
Trichopsocidae is a family of Psocoptera belonging to the suborder Psocomorpha. The family includes 11 species in two genera.-Sources:*Lienhard, C. & Smithers, C. N. 2002. Psocoptera : World Catalogue and Bibliography. Instrumenta Biodiversitatis, vol. 5. Muséum d'histoire naturelle, Genève....
) and Infraorder Psocetae
Psocetae
Psocetae is an infraorder of Psocoptera. It includes the families Hemipsocidae, Myopsocidae, Psilopsocidae and Psocidae.-Sources:*Lienhard, C. & Smithers, C. N. 2002. Psocoptera : World Catalogue and Bibliography. Instrumenta Biodiversitatis, vol. 5. Muséum d'histoire naturelle, Genève....
(families Hemipsocidae
Hemipsocidae
Hemipsocidae is a family of Psocoptera belonging to the infraorder Psocetae. Member of the family have the areola postica joined to the M vein by a crossvein, and their M vein is 2-branched. This family comprises twenty-four species in three genera.-Sources:...
, Myopsocidae
Myopsocidae
Myopsocidae is a family of Psocoptera belonging to the suborder Psocetae. This family is closely related to Psocidae, with which it share similar wing-venation, but from which it is distinguished by three-segmented tarsi.-Sources:...
, Psilopsocidae
Psilopsocidae
Psilopsocidae is a family of Psocoptera belonging to the infraorder Psocetae. Member of the family have a free areola postica and mottled wings. It is the only psocopteran family with records of wood-boring species. The family comprises one genus and seven species.-Sources:*Lienhard, C. & Smithers,...
and Psocidae
Psocidae
Psocidae is a family of Psocoptera belonging to the suborder Psocetae. Member of the family are easily recognised by their wing-venation, where the areola postica is fused to the M-vein, giving rise to the so-called discoidal cell. This family is closely related to Myopsocidae.-Sources:*Lienhard,...
).
External links
- National Barkfly Recording Scheme
- Psoco Net
- Tree of Life: Psocodea
- Archipsocus nomas, a webbing barklouse on the UFUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ IFASInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
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