How long after nits hatch do lice appear? - briefly
Mobile lice appear within 1–2 days after the egg hatches, reaching reproductive adulthood in roughly 7–10 days.
How long after nits hatch do lice appear? - in detail
The egg (nit) of Pediculus humanus capitis typically hatches after 7–10 days at ambient temperatures of 30–32 °C. Upon emergence, the nymph is translucent and measures about 1 mm. Within 24–48 hours the nymph begins feeding on blood, darkening in colour and becoming detectable on the scalp.
The nymph undergoes three successive molts, each lasting roughly 2 days. After the final molt, the insect reaches adult size (2–3 mm) and is fully capable of reproduction. Consequently, the first visible lice appear within one to two days after the egg cracks open, while mature, egg‑laying adults appear approximately one week after hatching.
Key points:
- Egg incubation: 7–10 days under optimal temperature.
- First nymph visibility: 1–2 days post‑hatch.
- Molting schedule: three molts, each ~2 days.
- Adult emergence: ~7 days after hatching.
- Detection threshold: adult or late‑instar nymphs are readily seen on hair shafts.
Temperature fluctuations, host grooming frequency, and hair density can accelerate or delay these intervals, but the outlined timeline represents the standard biological pattern.