Louse is a small, wingless insect that lives on birds and mammals, including human beings. Lice are parasites that feed on the animal on which they live. This animal is called the host. Lice cause severe itching and can spread disease.
There are two chief kinds of lice, chewing lice and sucking lice. Chewing lice, also called bird lice, have a mouth designed for chewing. They most commonly are found on birds and feed on the feathers, hair, or skin of the host. Chewing lice are 10 times more abundant than sucking lice and often occur on domestic animals, especially farm fowl. They do not attack human beings.
Sucking lice have sucking mouth parts. These lice pierce the host’s skin and feed on the blood of the host. Each leg of a sucking louse has a claw at the end. The louse uses its claws to attach itself to hairs on the body of the host.
Several species of sucking lice live on human beings. One species, Pediculus humanus, is found on human beings exclusively. There are two varieties of this species, the head louse and the body louse. Head lice, commonly called cooties, live in the hair of the host. They attach their nits (eggs) to hairs by means of a gummy substance. Head lice pass from one person to another through direct contact or shared use of combs, hats, and other items for the head. Body lice lay their nits in the seams of the host’s clothing. Body lice often remain with the clothing or bedding of an infected individual and tend to wander from the clothing of one person to that of another. Body lice can carry and transmit diseases. The most serious of these is epidemic typhus, which can cause death (see Typhus).
The best way to discourage sucking lice is to bathe regularly and to wear clean clothes. To eliminate lice from the body, physicians may recommend dusting the body with an approved pesticide for lice, or the use of certain lotions or shampoos. Hot-water washing will usually rid clothes of lice.
Insects called aphids are sometimes referred to as plant lice. Aphids feed on plant juices. See Aphid.
