Lice are small wingless insects. They have six legs with hook-like claws for grasping onto hairs. They feed on human blood. There are three types of lice.
- Head lice are common in children.
- Body lice are common in vagrants, live in clothing and only visit the skin to feed.
- Crab or pubic lice are found in the pubic hair area.
The short life of a head louse
- The louse begins as an egg, with a hard brown shell
- The egg hatches after 7–10 days, leaving behind the empty egg case, which appears white
- The baby louse takes10 days to grow into an adult, shedding its skin three times as it grows
- When the louse reaches adulthood, it is about the size of a sesame seed (about 3 mm long)
- The louse clings to hairs with its claws, and sucks blood from the scalp several times a day. If it is a female, it busies itself laying five eggs each night and attaching them to the base of hairs close to the scalp where they will be kept warm
- The louse keeps looking for any opportunity to get onto another head, by clambering across a ‘bridge’ of hair. It cannot jump
- After 30 days of being an adult, it dies
Written by: Dr Margaret Stearn
Edited by: Dr Margaret Stearn
Last updated: Friday, March 18th 2011
Useful contacts for Head lice
Click to see all the contacts that you may find useful in relation to head lice
983 people have
tackled this problem!
Tell us your thoughts
Did you find what you were looking for?
Add a comment
A problem shared is a problem halved: help others by sharing your frustrations or successes at tackling your health problem.
We have noticed that many of your queries are actually answered on the website, so please read carefully before submitting a comment. As all comments are moderated, there will be a delay before your comment appears. Please note that we cannot respond to individual requests for feedback.
In the UK, each month 20% of hairdressing salons see head lice in a client's hair
An estimated 5% of the UK population has head lice
Each year in the UK, the NHS and the general public together spend £29 million on head lice treatments
'Lousy', 'nitwit', 'nit-picking', 'nitty-gritty', 'go through something with a fine-tooth comb' - all these phrases come from lice
The average person with head lice has about 20 lice. During their 30-day life, 20 lice will lay 2652 eggs (Lancet 2003;361:99-100)
After mating, a female head louse keeps spare sperm in a special container in her body (spermatotheca), so that she does not have to bother with mating again, but can use the sperm she has kept (Lancet 2003;361:99-100)
Head lice are fairly speedy. They can move at 23 cm per minute (Lancet 2003;361:99-100)
Head lice have probably been annoying humans for at least 72 000 years (New Scientist 2003;23 Aug)