MODEL RELEASED. Head lice. Mother checking her teenage son's hair for head lice. Human head lice (Pediculus humanus capitis) are parasitic insects that can infest the human scalp and feed on human blood. An infestation of head lice can lead to numerous living and dead lice, and also lice eggs (nits) on the scalp, causing severe itchiness and skin inflammation. Treatment can be by the use of a special comb, or medicated shampoos, but careful examination of the scalp is needed to ensure that all the lice have been removed.