The crab louse infests the pubic regions, and is not easily transferred in school of childcare settings. The body louse, although a scourge to humanity throughout history through its ability to carry Typhus, is not common in the US because it is easily controlled through proper hygiene. Of these three, only the head louse is a major problem in schools. Head lice live among the hairs of the head close to the scalp. They are usually grayish in color, but may range from grayish-brown to rust or tan.
Adults are a little less than one-eighth inch long, about the size of a sesame seed.
They are flat, wingless, and have claws which grasp hair very firmly so that they will not fall out, or be washed out of the hair. Their eggs, called nits, are glued onto hair close to the scalp. These n its are tiny, silvery, and oval-shaped. They sometimes resemble dandruff, but dandruff can be easily removed, while nits are firmly attached. Nits hatch one week after being laid, reaching maturity in another 7-14 days.