Where do head lice live? - briefly
Head lice inhabit the human scalp, anchoring themselves to hair shafts close to the skin. They concentrate in warm, protected areas such as the nape of the neck and behind the ears.
Where do head lice live? - in detail
Head lice inhabit the human scalp, where they cling to hair shafts and feed on blood from the skin. The insects position themselves close to the base of each strand, typically within a few centimeters of the scalp, to maintain access to warmth and moisture. Their eggs, commonly called nits, are cemented to the hair shaft at an angle of 30–45 degrees, most often near the crown, behind the ears, and along the neck line. This placement protects the eggs from being dislodged by routine grooming.
The microenvironment preferred by adult lice includes:
- Warm temperature (approximately 30–34 °C) that supports metabolic activity.
- High humidity levels (above 50 %) that prevent desiccation.
- Proximity to sebaceous secretions, which provide a thin film of moisture on the scalp.
These conditions are consistently found on the scalp surface, making it the primary habitat. Lice can survive briefly on personal items such as combs, brushes, hats, pillowcases, and upholstered furniture, but they do not reproduce off the host. Survival off‑host is limited to 24–48 hours under optimal temperature and humidity; beyond this period, the insects die from dehydration.
Nymphs, the immature stage, remain on the hair shaft after hatching, feeding several times a day while remaining within the same localized area as the adult population. Their limited mobility ensures that the infestation stays concentrated on the scalp region rather than spreading to other body parts.
Overall, the head louse’s life cycle is tightly bound to the scalp’s anatomical and physiological characteristics, with all stages—egg, nymph, and adult—remaining attached to hair shafts and relying on the host’s skin environment for survival and reproduction.