Lice are human parasites (meaning they attach to us as their host) that feed on our blood, and they can be inadvertently transferred from one head to another. Pets and other animals can’t get head lice, and they are most commonly found in children, although adults are not immune. Approximately 6 to 12 million children aged 3-11 get head lice each year in the US alone. Put another way, that’s about one in 5 kids.
A single adult louse is quite small – about the size of a sesame seed – and their eggs are even smaller. This is why they can be very difficult to spot, especially in the early stages of an infestation. Adults are usually a white or grey-ish color, while eggs are usually tan, brown or yellow.
Lice are well adapted to living in human hair, and can be transferred from one person to another through contact. The most common form of transference is ‘head to head’ contact like touching an infected person’s hair and then your own, or using the same comb, for example. Individual lice can live for about 30 days on a human head, but will continue to multiply during that time.
Female lice reproduce by laying eggs (up to 4-8 per day) which attach onto hair shafts, and hatch into baby lice called nymphs in a week or so. Before hatching, the eggs need the warmth of a scalp to remain viable, and after hatching they require a supply of human blood to stay alive. After another week, nymphs mature into adult lice. Female adult lice can lay about 100 eggs in their lifetime, so lice can multiply very quickly!