Psocoptera

The order of insects Psocoptera, Spanishized as Psocoptera commonly known as book lice and bark lice >, are a paraphyletic order of small neopterous insects that are transparent gray, yellowish white, or dark brown in color, with a soft body, with or without wings, and these can be long or short. The name Psocoptera has been replaced by Psocodea in recent literature, with the inclusion of the older order Phthiraptera in Psocodea (as part of the suborder Troctomorpha). Some 3000 species have been described in between 226 and 345 genera according to the different bibliography; some of them live in human environments (houses, warehouses, barns, etc.) where they are frequent on moldy paper, from which their common name derives.

Features

Most psocopters are less than 6mm. Winged species have four membranous wings; occasionally the forewings are well developed and the hindwings are vestigial, while the hindwings far exceed the abdominal apex when the animal is at rest; In addition, the four wings remain in the roof when perched. The antennae are usually long and slender (filiform), made up of about 13 to 50 segments. The tarsi have 2 or 3 segments; the mouthparts are chewing, the compound eyes are underdeveloped in some species and generally have three ocelli, although they may not have them at all. The prothorax is greatly reduced in winged species. They have a characteristic gibbosity in the mesothorax. The winged do not usually fly; sometimes they fly in large numbers letting themselves be carried away by the air like aphids.

Biology and ecology

The metamorphosis is incomplete, they are paurometabolous hemimetabolous and the developing individuals (nymphs) are very similar to the adults but they always lack wings. They lay between 20 and 100 eggs in general, although there are also viviparous species and some present parthenogenetic reproduction. The eggs are laid singly or in groups and sometimes covered with silks or remains of material. Most species go through six developmental or nymphal stages. In some species no adults are known. The eggs usually hibernate; nymphs and adults rarely. Many are gregarious.

They live in environments with high humidity, generalizing environments with humidity higher than 75%. The best known species are those that live in buildings such as houses with humidity, or new houses before the walls dry out, barns, cellars, etc. These species generally lack wings and are frequent on paper and books that are or were damp, which is why they are known as book, dust or straw lice.

Species that live in the field, are found on plants, tree bark, under rocks, etc., and usually have well-developed wings.

Psocoptera feed on a variety of plant and animal materials such as fungal mycelia, damaged cereal grains, pollen, dead insects, and insect eggs. Those who live among the books feed on the fungus that grows on the glue.

Paraphilia

In the 2000s, morphological and molecular phylogenetic evidence has shown that parasitic lice (Phthiraptera) evolved within the suborder Troctomorpha, making Psocoptera paraphyletic relative to Phthiraptera. In modern systematics, Psocoptera and Phthiraptera are treated together in the order Psocodea.

Applied entomology

Due to their diet, they can constitute a harmful pest for human objects of plant origin. They typically attack paper. They are actually fungivores and damage the paper by feeding and scratching the fungi that grow on it.

Some species of psocids, such as Liposcelis bostrychophila, are common pests of stored food products. Psocids, among other arthropods, have been studied to develop new pest control techniques in food manufacturing. One study found that Modified Atmosphere Packaging (MAP) helped control the re-emergence of pests during the manufacturing process and prevented new infestations in final products reaching consumers.

Control

Since they require a certain degree of humidity, limiting environmental humidity (as well as leaks and flooding) in materials storage areas and libraries prevents their appearance and settling. They are attacked with a formula based on thymol and methanol in adequate and exact amounts.^{[citation needed]}