Lice

The scalp and hair of humans; they are obligate ectoparasites and cannot survive for long off a human host.

Strictly human blood, which they feed on several times a day.

They do not fly or jump; they move through direct head-to-head contact or via shared personal items. They lay eggs (nits) near the base of the hair shaft.

Risks include intense itching, scalp irritation, and potential secondary bacterial skin infections from scratching. They are not known to transmit systemic diseases. There are no known ecological benefits.