Psocoptera (Copeognatha, Corrodentia: Booklice or Psocids and their allies)
Hemipteroid insects with long, filiform antennae of 12–50 segments, sometimes secondarily annulate. Head with Y-shaped ‘epicranial suture’ usually present; post-clypeus inflated. Maxilla with 4-segmented palp and a rod-like lacinia which is partially sunk
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PSOCOPTERA
(COPEOGNATHA , CORRODENTIA: Booklice or Psocids and their allies)
Hemipteroid insects with long, filiform antennae of 12-50 segments, sometimes secondarily annulate. Head with Y-shaped 'epicranial suture' usually present; post-clypeus inflated. Maxilla with 4-segmented palp and a rod-like lacinia which is partially sunk into head-capsule; labial palps much reduced, 1- or 2segmented. Prothorax generally small; wing-venation simple, with few crossveins, but often with characteristic anastomoses between Rs and M and between M and Cu1a. Tarsi 2- or ]-segmented. External genitalia inconspicuous, cerci absent.
The Psocoptera are small or minute insects with rather soft, stout bodies and usually delicate, membranous wings. Brachypterous, micropterous and apterous forms are characteristic of the female or of both sexes of some species. Several apterous species of Liposcelis are often found among accumulations of books and papers. They are commonly known as booklice and feed on fragments of animal and vegetable matter or the paste of bookbindings. The order includes a number of domestic species which may feed on stored food products, natural history specimens, straw and chaff in barns and warehouses, or occur in thatches and haystacks. The majority of Psocoptera, however, occur outdoors on foliage, tree trunks, under bark, on weathered fences and palings, on fungi and among growths of algae and lichens. A few inhabit the nests of birds or mammals and are sometimes found among their plumage or fur (Mockford, 1967a, 1971). In general Psocids live on fragments of animal or vegetable matter, particularly on fungi, unicellular algae and lichens. Although sometimes stated to eat paper, certain species actually feed upon moulds growing there and in this way reveal the injury done to the paper. Most Psocids carry foreign matter entangled among their body-hairs and in this way disseminate fungal spores. Many live gregariously and clusters of individuals of various ages are sometimes met with on bark, each colony covered by a canopy of fine silken O. W. Richards et al., Imms’ General Textbook of Entomology © O. W. Richards and R. G. Davies 1977
PSOCOPTERA threads. The winged forms are curiously reluctant to take to flight but sometimes fly in considerable numbers and drift through the air after the manner of winged aphids. They are occasionally recorded as occurring in buildings in large swarms, the commonest species concerned being Lachesilla pedicularia. General accounts of the Psocoptera are given by Badonnel (1951) and Weidner (1972) and various aspects of their biology are discussed by Jentsch (1939), Medem (1951), Schneider (1955), Broadhead and Thornton (1955), Broadhead (1958) and New (1969, 1971). External Anatomy - The head (Fig. 304) is large and very mobile, with the 'epicranial sutures' more or less distinct. The compound eyes are markedly convex and protrude from the surface of the head; in apterous
FIG. J04
Frontal view of the head of a psocid
F, frons. C, post-clypeus. C1, ante-clypeus. L, labrum. M
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