How do lice appear in hair when examined with a comb? - briefly
When a fine-toothed comb is run through hair, live lice appear as tiny, flattened, tan‑brown insects that cling to the shaft, while their eggs (nits) show up as small, white‑to‑gray, oval shells cemented close to the scalp. The comb’s teeth trap both, making the infestation visible without magnification.
How do lice appear in hair when examined with a comb? - in detail
When a fine‑toothed lice comb is drawn through a head of hair, the insects and their eggs become visible as distinct particles caught between the teeth. The comb’s narrow spacing (typically 0.2–0.5 mm) separates each strand, allowing the comb to lift and retain any attached organisms.
Adult lice are about 2–4 mm long, resembling tiny, flattened, gray‑brown insects. Their bodies are translucent enough that the underlying hair shaft can be seen through them. Under good lighting, the abdomen may show a slightly darker hue due to the presence of blood meals. When the comb pulls an adult from a strand, the insect often appears as a small, elongated speck that may twitch briefly before falling.
Nits, the eggs, are smaller, measuring 0.8–1.0 mm. They are oval, firm, and have a smooth surface. Their color ranges from light tan when freshly laid to darker brown after a few days of development. Nits are firmly cemented to the hair shaft, usually within 1 cm of the scalp. When the comb catches a nit, it remains attached to the tooth, appearing as a tiny, bead‑like object. The cemented attachment can be confirmed by gently pulling the nit; it will resist removal unless the hair is broken.
Key visual cues during comb inspection:
- Size: Adults 2–4 mm; nits ≤1 mm.
- Shape: Adults elongated and flattened; nits oval and smooth.
- Color: Adults gray‑brown, semi‑transparent; nits tan to dark brown.
- Attachment: Nits glued close to the scalp; adults loosely cling to hair shafts.
- Movement: Adults may move briefly when dislodged; nits are immobile.
The comb also helps differentiate lice from hair debris. Dandruff flakes are larger, irregular, and easily lifted off without adherence to the comb teeth. Sebum or dust particles lack the consistent size and shape of lice and nits and do not remain attached after a single pass.
Repeated combing over the same section increases detection probability, as some lice may reattach after the initial pass. Thorough inspection typically involves combing each section from scalp to tip three times, then examining the comb teeth under magnification or a bright light source to confirm the presence of lice or eggs.