Lice (Cont.)

Lice Life Cycle

There are three forms of lice:
 
  • The egg (also called a nit)
  • The nymph
  • The adult.
     
(Click What Do Lice Look Like? to see pictures of the three different types of lice.)
 
The lice life cycle from egg to egg is approximately one month.
 
The Nit
Nits are head lice eggs. They are very small (about the size of a knot in thread) and hard to see. Head lice nits are often confused for dandruff or hair spray droplets. They are oval and usually yellow to white. Nits take about one week to hatch. Once hatched, they are white or clear in color.
 
Nymph
The nit hatches into a baby louse called a nymph. It looks like an adult louse, but is smaller. Nymphs mature into adults about seven days after hatching. To live, the nymph must feed on blood.
 
Adult Head Louse
The adult louse is about the size of a sesame seed, has six legs, and is tan to grayish-white. In people with dark hair, the adult louse will look darker. Female lice, which are usually larger than the males, lay eggs. To live, adult lice need to feed on blood. If a head louse or pubic louse falls off a person, it dies within two days. Body lice can live up to 10 days without feeding.
 

Signs and Symptoms of Lice

The most common symptom with any of the types of lice is itching. This is because the saliva of the lice causes an allergic reaction. Keep in mind that not everyone with lice will have symptoms.
 
Head lice can be anywhere on the scalp, but most commonly are seen behind the ears and on the back of the head near the neckline. When looking at the scalp, very few head lice are usually seen. This is because they move very quickly. However, there are usually many nits (lice eggs) at the base of the scalp (see Signs of Head Lice).
 
Pubic lice are generally found in the genital area on pubic hair, but may occasionally be found on other coarse body hair, such as hair on the legs, armpits, mustache, beard, eyebrows, or eyelashes. Infestations in young children are usually on the eyebrows or eyelashes (see Signs of Pubic Lice).
 
The most common symptom of body lice is also frequent intense itching. Long-term body lice infestations may lead to thickening and discoloration of the skin, particularly around the waist, groin, and upper thighs (see Signs of Body Lice).
 
(Lice Continued: Page 4)
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Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD