Head Louse

Human hair, particularly behind the ears and near the nape of the neck.

Human blood (they are obligate blood feeders).

Head lice spend their entire lives on the human scalp, feeding multiple times a day. They cannot fly or jump, and typically spread through direct head-to-head contact or, less commonly, through shared items like combs, hats, or hair accessories. Females lay eggs (nits) firmly attached to hair shafts.

Risks: Head lice infestations (pediculosis capitis) can cause intense itching, scalp irritation, and secondary bacterial infections due to scratching. They do not transmit diseases. Benefits: There are no known benefits of head lice to humans or ecosystems; they are solely parasites.