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Brief Summary

    Louse: Brief Summary
    provided by wikipedia
    "Lice" redirects here. For the infection, see Pediculosis. For the district of Diyarbakır Province in Turkey, see Lice, Turkey. For other uses, see Louse (disambiguation).

    Louse (plural: lice) is the common name for members of the order Phthiraptera, which contains nearly 5,000 species of wingless insect. Lice are obligate parasites, living externally on warm-blooded hosts which include every species of bird and mammal, except for monotremes, pangolins, and bats. Lice are vectors of diseases such as typhus.

    Chewing lice live among the hairs or feathers of their host and feed on skin and debris, while sucking lice pierce the host's skin and feed on blood and other secretions. They usually spend their whole life on a single host, cementing their eggs, which are known as nits, to hairs or feathers. The eggs hatch into nymphs, which moult three times before becoming fully grown, a process that takes about four weeks.

    Humans host three species of louse, the head louse, the body louse and the pubic louse. The body louse has the smallest genome of any known insect; it has been used as a model organism and has been the subject of much research.

    Lice were ubiquitous in human society until at least the Middle Ages. They appear in folktales, songs such as The Kilkenny Louse House, and novels such as James Joyce's Finnegans Wake. They commonly feature in the psychiatric disorder delusional parasitosis. A louse was one of the early subjects of microscopy, appearing in Robert Hooke's 1667 book, Micrographia.

    Overview
    provided by EOL authors
    Lice (Insecta: Phthiraptera) are small, wingless insects, permanently parasitic on mammals and birds. The order is one of approximately thirty major groups of insects, and is divided into four suborders, three of which (the Amblycera, Ischnocera, and Rhynchophthirina) are known as chewing or biting lice, and the fourth (the Anoplura) as sucking lice. Amblycera and Ischnocera are found on both mammals and birds where as species of Rhynchophthirina and Anoplura are confined to mammals. In total there are approximately 5,000 known species, of which just under 70% are recorded from a single host species.
    Phthiraptera Overview
    provided by EOL authors

    In the Phthiraptera, louse is used for the singular and lice are used for the plural.“There are more than 3, 000 known species of lice and…more remain undescribed” (Smith and Page, 1997).They are usually about 0.5-6 millimeters in length.They require a host to survive and would not last long without one.Lice lack wings and mostly feed on skin or blood.Depending on the species, they feed by sucking or chewing.They can be found on “every avian and mammalian order except for monotremes (the platypus and echidnas), bats, whales, dolphins, porpoises, and pangolins” (Wikipedia, 2013).For mammals, the lice will attach their eggs with saliva.For birds, the lice will lay their eggs in spots that the birds cannot reach with their beaks.Lice tend to be more aggregated when living on bird species.They undergo incomplete metamorphosis.Within a month, the nymphs will molt three times before becoming an adult.

Comprehensive Description

Systematics or Phylogenetics

    Systematics or Phylogenetics
    provided by EOL authors

    Recent mophological (Yoshizawa & Johnson 2006) and molecular evidence (Johnson et al. 2004) has shown that the parasitic lice (Phthiraptera) evolved from within the psocopteran suborder Troctomorpha. In modern systematics, Psocoptera and Phthiraptera are therefore treated together in the order Psocodea (Bess et al. 2006).