How many days do lice hatch from eggs? - briefly
Lice eggs typically hatch in 7–10 days when kept at normal indoor temperatures.
How many days do lice hatch from eggs? - in detail
Lice eggs, commonly called nits, require a specific incubation period before the emerging nymphs become mobile. Under normal ambient conditions (approximately 30 °C or 86 °F and 70 % relative humidity), the developmental interval ranges from 7 to 10 days. The exact duration varies among species:
- Pediculus humanus capitis (head lice): 7–9 days.
- Pediculus humanus corporis (body lice): 8–10 days.
- Pthirus pubis (pubic lice): 8–10 days.
Temperature is the primary factor influencing the timeline. At lower temperatures (around 20 °C or 68 °F), development can extend to 12–14 days, while higher temperatures (above 35 °C or 95 °F) may shorten the period to 5–6 days, provided humidity remains adequate to prevent desiccation.
The egg’s structure also affects hatching. The operculum, a cap-like covering, detaches when the embryo is fully formed. Enzymatic activity within the embryo weakens the operculum, allowing the nymph to emerge. The nymph emerges as a miniature adult, lacking fully developed reproductive organs, and requires an additional 5–7 days of molting to reach reproductive maturity.
Factors that can disrupt the normal schedule include:
- Chemical treatments: Insecticidal agents may damage the embryo, causing premature death or delayed hatching.
- Mechanical removal: Physical extraction of nits before completion of development eliminates the future nymph.
- Host grooming: Excessive combing can dislodge nits, reducing the number that successfully hatch.
Understanding the precise incubation window assists in timing interventions. Effective treatment schedules typically repeat after 7–10 days to target newly emerged nymphs that survived the initial application.