Head lice live for around 30 days and will spend their entire life on a human ‘host’ (this may be one or more people over its lifetime).
The Egg
The female louse, once fertilised by a male louse, will a number of eggs, carefully gluing each one to the base of the hair shaft where the temperature is right. After approximately 7 days a nymph will emerge from the egg leaving behind an empty egg shell (the nit) that remains glued in position.
The Nymph
Once hatched, the nymph will go through three stages of development, shedding its skin (moulting) each time (every three days). After approximately 10 days the louse becomes an adult and is able to start the reproduction cycle again.
The Adult Louse
The adult louse will live for a maximum of 30 days, feeding and reproducing on the scalp. Females can lay 5-10 eggs per day but will lay fewer, as she gets older.
There have been no recent studies looking at the incidence of head lice, but it is thought to be on the increase. Incidence is thought to higher in winter.
All ages of people can catch head lice but the peak age is 7-8 years (Downs 2004) and incidence is much lower in adults.
Head lice have been around for as long as humans and evidence of head louse infections have been found on 10,000-year old mummies.
The scientific name for a head louse is pediculus humanus capitis and a head louse infection is sometimes referred to as pediculosis.
The number of head lice on an infected head can vary greatly, but the average number of adult lice is often quoted as 10. In some cases hundreds of lice can be found and recently there was a report of 2657 lice on one head!
A female head louse only needs to mate once to be able to lay fertilised eggs for the rest of her short life.
You cannot catch head lice from pets – they can only live on humans.
Head lice cannot jump or fly, they move from head to head by walking (at an average speed of around 10cm per minute).
Lice breathe through holes on the side of their bodies, which they can close when you wet your hair so that they don’t drown.
People with all types of hair get head lice – straight or curly, light or dark, even dirty or clean. These things may make a difference when it comes to detecting head lice but don’t make a difference to catching them!
It is possible to have a head lice infection for months without realising.
Head lice feed on human blood, piercing the scalp to feed on blood several times a day.
Head lice have claws on the end of each leg specially adapted for holding onto human hair.
Head lice shed their skin 3 times before they become adults because their skin cannot stretch as they grow.
Adult female head lice can lay 5-10 eggs per day, but will lay less as they get older.
The scientific name for a head louse is pediculus humanus capitis and a head louse infection is sometimes referred to as pediculosis.