Head lice has been around for thousands of years, even the ancient Egyptians shaved their head due to the blood sucking little insects. Head Lice will crawl into any human’s hair to feed on very small amounts of blood from the scalp which will result in scratching. Head Lice have no wings, cannot jump and can only reinfest by close contact.
After mating, the female Head Lice (aka Louse) lay eggs (aka Nits) very close to the scalp or base of the hair, for the Nit to survive. Preferred areas are behind the ears and hair line of the lower neck. In colder temperatures the egg (aka Nit) will be closer to the scalp whereas warm climates, eggs are generally laid further down the hair shaft. A Nit is tan in colour and usually white after hatching.
The Head Lice breeding cycle is actually quite rapid. A Louse (female) can lay approx 100 eggs every 10 days which hatch 7 to 10 days later.
Parent Information Sheet - http://www.health.nsw.gov.au/environment/headlice/Pages/information.aspx