How do head lice and nits look? - briefly
Adult head lice measure 2–3 mm, are gray‑white, wingless insects that move quickly and cling to hair shafts. Nits are the lice’s eggs, oval, about 0.8 mm long, appearing white or yellowish and firmly attached to hair near the scalp.
How do head lice and nits look? - in detail
Head lice are small, wing‑less insects that measure about 2–3 mm in length. Their bodies are elongated and flattened, facilitating movement through hair shafts. The exoskeleton ranges from gray‑white to tan, often appearing slightly translucent when the insect has recently fed. Six legs end in claw‑like tarsi, each equipped with a single hook that grasps individual strands of hair. Antennae are short, bearing sensory organs for detecting temperature and carbon dioxide. Live specimens move quickly, exhibiting a characteristic “shaking” motion when disturbed.
Nits are the eggs laid by adult females and are attached firmly to the base of a hair strand, typically within 1 cm of the scalp where temperature is optimal for development. Each nit measures 0.8–1 mm in length and has an oval shape. The shell is smooth, glossy, and initially appears white or creamy; as the embryo matures, the nit darkens to a yellow‑brown hue. The attachment point is a cement‑like secretion that resists removal by simple combing. Unlike dandruff, which flakes off easily, nits remain anchored until hatching, usually after 7–10 days.
Key visual distinctions:
- Size: adult lice 2–3 mm; nits ≤1 mm.
- Color: lice gray‑white to tan; nits white → yellow‑brown as they age.
- Shape: lice elongated with visible legs; nits oval, smooth, no legs.
- Location: lice move freely on scalp and hair; nits fixed near scalp, often at the hair base.
- Mobility: lice exhibit rapid crawling; nits are immobile, firmly cemented.
When inspecting a scalp, look for live insects crawling among hair, especially behind the ears and at the nape. Examine hair shafts closely for tiny, attached ovals that do not detach when brushed. These characteristics provide a reliable basis for identifying infestation.