Female lice lay six to seven eggs (nits) per day and may lay a total of 50 to 100 eggs during their life which may last up to 40 days. Adults can only survive one to two days without a blood meal. The nymphs and adults all have piercing-sucking mouthparts which pierce the skin for a blood meal. The reaction of humans to louse bites can vary considerably. Persons previously unexposed to lice experience little irritation from their first bite. After a short time individuals may become sensitized to the bites, and may react with a general allergic reaction including reddening of the skin, itching, and overall inflammation.