What do human lice look like? - briefly
Human lice are tiny, wing‑less insects about 2–4 mm long, with a flattened, elongated body that is gray‑brown to reddish‑brown in color and covered by fine, translucent hairs. They possess six legs, each ending in clawed tarsi that enable them to grasp hair shafts.
What do human lice look like? - in detail
Human lice are small, wing‑less insects measuring 2–4 mm in length. The body is flattened laterally, facilitating movement through hair shafts. Color ranges from light gray to brown, often darkening after a blood meal.
The head consists of a rounded, sclerotized cap covering the brain. Compound eyes are present on each side of the head, providing limited vision. A pair of short, segmented antennae extends forward, each bearing sensory organs for detecting temperature and carbon dioxide.
The thorax bears three pairs of legs, each ending in clawed tarsi that grasp hair strands securely. Legs are relatively long compared to body size, allowing rapid locomotion. The abdomen is segmented, containing a dorsal exoskeleton and ventral plates that protect internal organs. In females, the abdomen expands to accommodate eggs (nits) laid close to the scalp; males possess a slightly narrower abdomen.
Nymphal stages resemble adults but are smaller and lack fully developed reproductive organs. They molt three times before reaching maturity, each molt increasing size and pigmentation. Head lice (Pediculus humanus capitis) differ from body lice (Pediculus humanus humanus) primarily in size—head lice are marginally smaller—and in the location of egg attachment; head lice attach nits to hair shafts, whereas body lice attach them to clothing fibers.
The exoskeleton is composed of chitin, providing rigidity and protection. Respiratory openings (spiracles) are located laterally on the thorax, allowing gas exchange while the insect remains concealed within hair or clothing. Overall morphology enables efficient clinging to host hair, rapid movement, and survival in the human environment.