How many lice are in an egg? - briefly
Each louse egg (nit) contains a single developing louse. Upon hatching, one nymph emerges from the egg.
How many lice are in an egg? - in detail
Each egg laid by a head‑lice (Pediculus humanus capitis) contains a single embryo. The ovoid structure, typically 0.8 mm in length, houses one fertilized egg surrounded by a protective chorion. Upon deposition on a hair shaft, the egg remains attached by a cement‑like substance secreted by the female.
Key biological facts:
- Embryonic content: one developing nymph.
- Egg dimensions: 0.5–1 mm long, 0.2 mm wide.
- Incubation period: 7–10 days at normal human scalp temperature (≈ 35 °C).
- Hatching: the emerging nymph emerges fully formed, ready to feed within 24 hours.
The presence of a single organism per egg is consistent across all stages of the life cycle. No egg contains multiple larvae; multiple eggs may be found clustered on a single hair, but each remains an independent unit. Detection methods, such as visual inspection with a fine-tooth comb, rely on this one‑to‑one relationship to estimate infestation severity.