Which appears first: nits or lice? - briefly
Nits are laid before any lice hatch, so the eggs are present first. Adult lice deposit the nits, which then develop into nymphs and mature insects.
Which appears first: nits or lice? - in detail
The egg, commonly called a nit, is the initial stage of the head‑louse life cycle. An adult female deposits each egg on a hair shaft, attaching it with a cement‑like substance. Within 7–10 days the egg hatches, releasing a nymph. The nymph resembles an adult but is smaller and lacks full reproductive capacity. After three molts, occurring over approximately 9–12 days, the nymph matures into an adult louse capable of laying new eggs.
Key points of the developmental sequence:
- Egg (nit) attachment to hair shaft.
- Incubation period: 7–10 days at typical indoor temperatures.
- Hatching into first‑instar nymph.
- Three successive molts, each lasting 2–3 days.
- Emergence of sexually mature adult.
Therefore, the egg stage inevitably precedes the presence of a living louse. Any detection of lice on a host must be preceded by an earlier deposition of eggs, even if the eggs are not yet visible. The timing of appearance depends on environmental conditions, but the chronological order remains constant: nit first, then louse.