Head Lice - The Facts

When you are dealing with head lice it can help if you understand how they operate.

  • Head lice are wingless insects that live on the scalp holding on to the hair.

  • They are greyish in colour but turn darker after feeding from the blood in the scalp.

  • Head lice are 2 to 3 mm in size: the male is smaller than the female.

  • Lice live close to the scalp where they feed on blood and this bite can cause itching.

  • They especially love warm spots: behind the ears or around the neck.

  • Adult lice can live for as long as a month with females laying up to 5-6 eggs a day (about 150 eggs in a lifetime)

  • These eggs hatch after about 7 days and around 9 days later they are mature and the females can lay eggs.

  • Baby lice take 10 days to mature and only after that are they able to reproduce

  • Nits (lice eggs) are the empty egg cases left on the hair after the lice have hatched and are pale in colour

  • Lice spread when heads come into contact so sleepovers, after-school activities, playing with friends and visiting family are often the most common places for children to pick them up and pass them on

  • A louse cannot remain viable away from the head for more than about 12-14 hours

Myth: Head lice jump from one head to another

Head lice can only be passed by direct head-to-head contact - they cannot jump, fly, hop or swim. 

Myth: Head lice can be caught by sharing things like hairbrushes, towels or bedding

Head lice only survive on heads, dying quickly away from their food source. Adults and nymphs can only survive for 8-24 hours without feeding or they become too dehydrated to survive. They can only be caught from human contact. 

Myth: Head lice prefer clean hair

Having head lice has nothing to do with personal hygiene, head lice can live on all types of hair and no preference exists between clean or dirty hair. 

Myth: Shaving a child's head is the best way to get rid of head lice

Lice like to live close to the scalp and can survive on hair as short as 2mm long, so cutting hair short won't necessarily help and can be very traumatic to the child. 

Myth: Animals can carry and pass on head lice

Head lice can only live on human beings, people can't catch them from animals

Myth: Head lice are only caught from other children at school

A lot of head lice infections are caught from family and friends in the home and local community, not just at school - parents typically start to worry about lice when children go back to school so they are more likely to identify an infection and presume the lice were caught there.

Source: 1995: Burgess IF.  Human lice and their management.  Advances in Parasitology 1995; 36: 271-342.

Chunge RN, Scott FE, Underwood JE, Zavarella KJ.  A pilot study to investigate transmission of headlice.  Canadian Journal of Public Health 1991; 82: 207-208,