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Related to louse: body louse, crab louse, lice, Lowes


louse, common name for members of either of two distinct orders of wingless, parasitic, disease-carrying insects. Lice of both groups are small and flattened with short legs adapted for clinging to the host.

The sucking lice, of the order Anoplura, are external parasites of humans and other mammals, feeding on blood by means of their piercing-and-sucking mouthparts. The group includes the body lice and head lice, considered varieties of the same species, Pediculus humanus, and the crab, or pubic, louse, Phthirus pubis, named for its crablike appearance. A female sucking louse lays about 300 eggs, or nits, in her lifetime, cementing them to body hairs and underclothing. The larva resembles the adult; the life cycle takes about 16 days. Sucking lice infestations are common in crowded living conditions and where clothing is not changed or washed frequently. Body lice may transmit rickettsial diseases (see rickettsia) and bacterial infections such as relapsing fever; infection results from scratching the crushed louse or its feces into the skin.

The chewing, or biting, lice, of the order Mallophaga, have chewing mouthparts and feed on hair, skin, or feather fragments of the host. They attack birds, rodents, and domesticated animals. Although they do not actually puncture the skin, and thus are scavengers and not true parasites, they often multiply so rapidly that they irritate, weaken, and may even kill the host. The chicken louse, Menopon pallidum, if left uncontrolled, can be a major problem in poultry production. Chewing lice may produce 6 to 12 generations annually. The eggs hatch into rapidly developing young in which metamorphosis is incomplete, as in many parasites.

The book louse is a tiny, wingless, cosmopolitan insect that damages books by feeding on glue, paste, and paper. It resembles lice but is not related, belonging to the order Psocoptera. The aphid is sometimes called plant louse.

Lice are classified in the phylum Arthropoda, class Insecta, orders Anoplura and Mallophaga.


See bulletins of the U.S. Dept. of Agriculture.

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(invertebrate zoology)
The common name for the apterous ectoparasites composing the orders Anoplura and Mallophaga.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. any wingless bloodsucking insect of the order Anoplura: includes Pediculus capitis (head louse), Pediculus corporis (body louse), and the crab louse, all of which infest man
2. biting or bird louse any wingless insect of the order Mallophaga, such as the chicken louse: external parasites of birds and mammals with biting mouthparts
3. any of various similar but unrelated insects, such as the plant louse and book louse
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Research suggests that environments frequented by homeless persons (e.g., homeless shelters, where there is close bodyto-body contact and where clothing hygiene is lacking) promote louse transmission (2,5).
Although re-infestation caused by a lone louse in the house is extremely rare, it is not impossible.
The achievement is expected to yield new insights into louse - and human - biology and evolution.
Dr Daniel Thomas, of the National Public Health Service for Wales and lead scientist for the project, said, 'Nowadays, head lice are regarded as more of a social than a health issue but they are a real nuisance for parents and cause discomfort among children who have them.': Advice on treating nits:Treat yourself or members of your family for head lice only after you've found a live louse. In the UK, head lice are becoming resistant to chemical treatments, so it is difficult to say which treatment will work best for you.
Elston said, "eyelash nits are usually a manifestation of pubic louse infestation, not head louse infestation.
There are three types of bloodsucking lice, one biting louse and one tail louse.
A: The head louse is a greyish-brown insect about 2.5mm long and is usually found on the scalp.
The common head louse, Pediculus humanus capitis, is the most prevalent parasitic infestation of humans in the United States and Europe.
Ten to 12 million Americans each year are diagnosed with lice infestation, and two new alternative products are available to get rid of lice and nits (louse eggs) safely and effectively.
(4) "Prevalence of head louse infestation among school-aged children is usually reported as under 10% but may be as high as 40% in certain circumstances and locations." (6) (p 183)
Nymph: The egg hatches into a baby louse called a nymph.