What do lice look like on a human head? - briefly
Lice are tiny, wingless insects about 2–3 mm long, with a flattened, oval body that ranges from tan to gray and six legs ending in tiny claws for gripping hair shafts. Their movement appears as a rapid, jerky crawl, and they lay oval, white eggs (nits) firmly attached to each strand near the scalp.
What do lice look like on a human head? - in detail
Lice that infest the human scalp are small, wing‑less insects measuring 2–4 mm in length. Their bodies are flattened laterally, which allows them to move easily through hair shafts. The coloration ranges from grayish‑white to light brown, often appearing translucent when the insect is unfed and becoming darker after a blood meal.
Key visual features include:
- Head: Small, rounded, and positioned near the front of the thorax; eyes consist of simple ocelli that are difficult to see without magnification.
- Antennae: Six segmented, slender, and mobile, extending forward from the head.
- Thorax: Broad, housing three pairs of legs, each ending in claws adapted for gripping hair strands.
- Abdomen: Segmented, slightly wider than the thorax, with a smooth, glossy surface; after feeding, the abdomen may swell with blood.
Eggs, known as nits, are oval, about 0.8 mm long, and firmly attached to the hair shaft near the scalp. They are white or yellowish and become more opaque as the embryo develops. Nits are positioned at an angle of roughly 30–45 degrees from the hair shaft, a characteristic that helps differentiate them from hair debris.
Typical locations on the head:
- Behind the ears
- At the nape of the neck
- Near the hairline and forehead
- Along the crown where hair is denser
Movement is rapid; lice can crawl at 0.5 mm per second, often appearing as brief, darting shadows when the scalp is examined under a light. Their legs enable a firm grip, preventing easy dislodgement by brushing.
Distinguishing head lice from other species:
- Body lice: Larger (3–5 mm), less flattened, and primarily found on clothing rather than directly on hair.
- Pediculus capitis (head louse): Adapted specifically to hair shafts, with claws sized to grasp human scalp hair.
Recognizing these physical characteristics facilitates accurate identification and appropriate treatment.