How many days does it take for lice to hatch? - briefly
Lice eggs typically hatch in 7–10 days under normal temperature and humidity conditions.
How many days does it take for lice to hatch? - in detail
The incubation period for head‑lice eggs, also called nits, typically ranges from 7 to 10 days under normal conditions. Temperature, humidity, and the species influence the exact duration.
- Optimal temperature: 30 °C (86 °F) accelerates development; lower temperatures lengthen it.
- Relative humidity above 70 % promotes faster hatching; dry environments can delay emergence by several days.
- Pediculus humanus capitis (common head louse) follows the 7‑10‑day window; body lice (Pediculus humanus corporis) exhibit a similar timeframe.
During the embryonic stage, the embryo consumes the yolk within the egg, forming a fully developed nymph ready to emerge. The nymph requires an additional 24‑48 hours of feeding on blood before it can molt into an adult.
If environmental conditions are unfavorable—such as temperatures below 20 °C (68 °F) or humidity under 50 %—the hatch time may extend to 12‑14 days. Conversely, warm, moist settings can shorten it to as few as six days.
Understanding these variables aids in timing treatments effectively; most pediculicide regimens recommend a second application 7‑9 days after the first to target newly emerged nymphs before they mature.