Head Lice information and FAQ

What do head lice look like?

Human lice are minuscule, wingless insects, about 1 – 5mm long (about the size of a sesame seed) and are either light grey or dark brown in appearance (depending on how much blood has been ingested). The live eggs are dark brown and can be found very close to the scalp. Dead eggs are white.

Head lice have six jointed legs that end in small claws which enable them to move through the hair quickly and easily. Most importantly this enables them to cling to the hair to prevent them being dislodged.

Care should be taken to remove all eggs as no-one wants nits in their hair, dead or alive.

What causes head lice?

While head lice are extremely well adapted to moving through the hair of their host, they cannot jump nor crawl very far.

Head lice are generally spread by head to head contact or through sharing brushes, combs, pillows and head wear etc. There is also a possibility of picking up a stray hair that has fallen out with a nit attached from headrests and backpacks etc.

Head lice affect people from all walks of life and all socio-economic classes. Contrary to popular belief head lice actually prefer clean hair as greasy hair is difficult for lice to attach their eggs to. Regular washing will not prevent or deter head lice.

Head lice do not feed on anything but human blood and do not infect pets or other animals.

Where do head lice come from?

Head lice are a human parasite and have probably been around since time began. They can only survive on humans and so therefore do not reside in the ground or on pets. Head lice are not fussy where they live as long as it is clean so they can attach their eggs, and simply travel from host to host.

How do I know if I have Head Lice?

Lice are usually found at the nape of the neck or behind the ears so check here first to identify whether or not there is a presence of live lice.

The head louse feeds by biting into the scalp and then inserting its proboscis into a blood vessel along with saliva to stop the blood from clotting (much like a mosquito). It is this saliva that causes the irritation that leads to the itching.

Do I need to wash everything in hot water and rid my home of lice and eggs?

Adults and nymphs are only able to survive for 2-3 days off the host in optimal conditions. Under normal circumstances however this is more likely to be measured in hours rather than days as the adult louse is highly susceptible to dehydration and will quickly starve.

Eggs can survive away from the head for up to 7 days but will not hatch without the warmth of a human host. With this in mind it is fairly obvious that compulsively cleaning is not required in preference to killing all the adult lice and eggs. It is preferable to take preventative steps to ensure they don’t return to the head.

Do not be persuaded to use pesticide bombs that unnecessarily expose your family to dangerous chemicals. Vacuuming and wiping surfaces with hot soapy water is all that is required.

What are the life cycle and incubation periods of head lice?

The first stage of the life of a head louse is the egg, which the adult attaches to the hair with nit glue very close to the scalp for warmth. This glue is very strong and makes manual removal very difficult.

In 5-9 days the egg hatches into the nymphal stage which is the early stages of the adult louse. The term ‘nit’ refers to the empty shell left behind once the egg has hatched. The nymph immediately seeks out a suitable place to feed. Over the next 7-10 days he nymphs will shed their exoskeleton in three separate metamorphoses before they mature into adult lice.

Once mated, the adult female louse can then lays around 3-4 eggs a day until the end of her adult life (around 30 days).

Can head lice be drowned in water?

Head lice are well adapted to moving through the hair and have hooks that they use to latch on for dear life. In the water they are exactly the same except they also close their breathing holes, which they are able to do for half an hour. To drown head lice you would need to submerge your head in water for up to 8 hours.

You have as much chance of catching lice in water as you do in any other environment where the hair can fall out with the nit attached.