The head louse (Latin: Pediculus humanus capitis) is a parasite inhabiting hair on the head and feeding on human blood, which it sucks from the scalp. It has 6 legs and is about 3mm long. It thrives at temperatures of 82° to 84°F, so it likes to stay close to the scalp, and often cannot be seen at a glance.
Lice cannot fly or jump. They are normally transferred during direct contact from head to head, which is why they are frequently spread in schools and summer camps, where children work or play with their heads close together.
The female head louse can lay up to 10 eggs (called nits) a day, and they glue them to the hair shaft close to the roots. The nits are less than 1mm in length, and almost opaque. The larvae come out after around 8 days and a new generation is born every three weeks.