Head louse (eggs known as nits)

Exclusively the human scalp and hair, remaining close to the scalp for warmth.

Obligate parasites that feed exclusively on human blood several times a day.

They cannot fly or jump; they move by crawling. Eggs (nits) are cemented to the hair shaft. Life cycle includes egg, three nymphal stages, and adult.

Cause intense itching and scalp irritation due to an allergic reaction to saliva. While they do not spread disease, secondary infections can occur from scratching. No ecological benefits to humans.