How to differentiate a louse and a nit? - briefly
A louse is a moving adult insect visible crawling on the scalp, whereas a nit is the immobile, oval egg attached firmly to a hair shaft close to the skin.
How to differentiate a louse and a nit? - in detail
A louse is a living, wing‑less insect that moves actively on the scalp or body hair. It measures 2–4 mm in length, has a flattened body, six legs with claws adapted for gripping hair shafts, and a brown‑ish to gray coloration. A nit is the egg of a louse; it is an immobile, oval or teardrop‑shaped structure about 0.8 mm long, firmly attached to the hair by a cement‑like substance.
Key visual distinctions:
- Size – adult lice are roughly three to five times larger than nits.
- Shape – lice have a distinct head, thorax, and abdomen, while nits appear as smooth, elongated capsules.
- Color – live lice exhibit a darker, mottled hue; nits are typically white, tan, or translucent until they hatch.
- Attachment – nits are glued to the hair shaft near the scalp, often at a 45° angle; lice are free‑moving and can be seen crawling.
Microscopic examination reveals further differences. Under magnification, a louse shows segmented legs, antennae, and visible eyespots. A nit displays a smooth shell with a clear operculum (the opening through which the nymph emerges) and no appendages.
Mobility provides an additional clue. Lice can walk, climb, and even jump short distances when disturbed. Nits remain stationary; attempting to pull a nit off the hair requires a gentle, steady force, and the attached cement may break only with a specialized nit‑comb.
Practical detection steps:
- Part the hair close to the scalp with a fine‑toothed comb.
- Examine each section on a white background.
- Identify live insects by their movement and shape.
- Locate attached eggs by their fixed position and coloration.
- Use a magnifying lens if necessary to confirm the presence of legs or an operculum.
Understanding these characteristics enables accurate identification, which is essential for effective treatment and prevention of reinfestation.