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PSOCOPTERA (= CORRODENTIA) <General Characteristics -- <Images> & <Juveniles> [Latest
Classification] Please refer also to the following
links for details on this group: Psocoptera.-- Pearman
(1932) noted that several psocid species were predaceous on Coccidae,
particularly mealybugs. They feed
also on various insect eggs and possibly on small aphids. However, other researchers believed that
their food consists mostly of the wax secretions of the scale insects rather
than the body contents. They are
small soft-bodied insects, most being <6 mm long. Three are ca. 72 genera and 340 species
known in the United States and Canada.
They have been referred to as "bark lice," but are known to
frequent an array of habitats. Eggs are laid singly or in clusters, sometimes covered
with silk or debris. Most species
have 6 nymphal instars. These insects that are
commonly known as booklice, barklice or barkflies. They date from the Permian
period, 294–249 million years ago. They are often considered to be the most
primitive of the Hemiptera-type insects. Their name originates from the Greek
word psokos which means gnawed or rubbed and ptera meaning
wings. There are more than 5,511 species in 41 or 42 families in three
suborders. Many of these species have only been recently described. They range in size from 1.1-10.2
millimeters in length. The species known as
booklice derive their common name from being usually found around old books
and they feed upon the paste in the binding. Barklice are harmless and found
on trees, where they feed on algae and lichens. None are currently considered
endangered. Rather they appear to be
extending their range as in 2007, Atlantopsocus adustus, native to
Madeira and the Canary Islands, was found in southwestern England. All
are scavenging insects with a a generalized body shape. They feed mainly on fungi,
algae, lichen, and organic detritus. They have chewing mandibles, and the
central lobe of the maxilla is modified into a thin rod, which is used to
support the insect while it scrapes up detritus with its mandibles. They also
have a swollen forehead, large compound eyes, and three ocelli. Some species
are able to spin silk from glands located in their mouth. The forewings range to 1.6 times as long as the hindwings, and all four
wings have a simple venation pattern, with few cross-veins. The legs are thin
and suited for walking, rather than gripping, as is found in the true lice.
The abdomen has 9 segments, and no cerci are present. There is often much
variation in the appearance of individuals within the same species. Many have
no wings or ocelli, and may have a distinct shape to their thorax. Other,
variations are also known, such as changes to the development of the setae.
The purpose of such changes is uncertain, but their function appears to be
different from similar variations found in the Homoptera . However, many
species are parthenogenic, and the presence of males may vary between
different races of the same species. The eggs are laid in
tiny crevices or on foliage, although a few species are known to be
viviparous. The young or nymphs
emerge as miniature, wingless versions of the adult. These usually molt six
times before reaching the adult stage. The total lifespan is short and hardly
ever more than a few months. References: Please refer to <biology.ref.htm>, [Additional references
may be found at: MELVYL
Library] García, A. N. Aldrete. 2006. "New genera of
Psocoptera (Insecta), from Mexico, Belize and Ecuador (Psoquillidae, Ptiloneuridae,
Lachesillidae)". Zootaxa 1319: 1–14. Hoell, H.V., Doyen, J.T. & Purcell, A.H. 1998. Introduction to Insect Biology and
Diversity, 2nd ed.. Oxford University Press. pp. 404–406. Lienhard, C. & C. N. Smithers. 2002.
"Psocoptera (Insecta): World Catalogue and Bibliography". Instrumenta
Biodiversitatis (Muséum d'histoire naturelle, Geneva) 5. Meyer, J. R.
2005. Psocoptera". North
Carolina State University O'Toole, C.
2002. Firefly Encyclopedia of Insects and Spiders. Toronto: |