How often do head lice feed? Although it is unclear exactly how often, it is likely that they feed four to six times per day. This makes it extremely difficult to eradicate head lice from the scalp. Lice are able to survive for several days on the head of an infected person. However, if they only feed four times per day, they will likely die quickly.
When head lice are hungry, they move close to the skin and puncture it with their mouthparts. They then add saliva to the wound to keep it from clotting. This blood is then ingested through two tiny pumps on their head. The blood stream exits their mouths as a thin thread. The darker it is, the more recent the meal was.
Adult head lice live for about 30 days. The female louse can lay eight or nine eggs per day. They feed on blood to grow. Adult lice reproduce rapidly and lay around six to nine eggs per day. They feed on human blood in order to survive. The nits hatch in seven to nine days and need a blood meal to grow.
Because head lice cannot fly or jump, they spread easily by close head-to-head contact. They can also be passed on clothing and personal items. People with head lice are at the highest risk of contracting them.