Although there are many types of lice, the head louse, or pediculus humanus capitis, is a parasitic insect that benefits while its host is harmed. Pediculus humanus capitis is an ectoparasite, meaning it is only found on the outside of the body, and they are only hosted by humans.

​

Head lice (the plural form of louse) can be found on the human head and less often on the eyebrows and eyelashes. Lice feed on human blood several times a day and live close to the scalp to maintain their body temperature.