How do lice crawl on the head? - briefly
Lice advance by anchoring their clawed legs to individual hair strands and pulling the body forward in quick, alternating steps, effectively “walking” along the shaft. This locomotion relies on coordinated leg movements and strong grip rather than crawling on skin.
How do lice crawl on the head? - in detail
Head lice (Pediculus humanus capitis) travel across the scalp by means of six short, jointed legs ending in curved claws. Each claw interlocks with the cuticle of a hair shaft, allowing the insect to grip, release, and reposition itself without slipping. The movement cycle consists of three stages:
- Attachment: The forelegs press the claws against the hair surface, generating friction that holds the louse in place.
- Propulsion: The middle and hind legs push backward, extending their joints while the forelegs remain anchored. Muscular contraction of the thoracic segments translates into a forward thrust of the body.
- Release and repositioning: The forelegs relax, the claws disengage, and the cycle repeats, advancing the insect a few millimeters per stride.
Sensory organs on the antennae detect temperature, carbon‑dioxide, and tactile cues, guiding the louse toward favorable zones such as the warm, moist region behind the ears. The head’s dense hair provides a network of parallel shafts, creating a three‑dimensional pathway that the insect exploits by alternating between vertical climbs and horizontal traverses. The combination of claw morphology, coordinated leg motion, and environmental sensing enables efficient locomotion across the human scalp.