How many days do lice live? - briefly
«Lice» survive about one month on a human host; adult individuals live roughly 30 days, and the complete life cycle from egg to death spans 4–6 weeks.
How many days do lice live? - in detail
Lice, belonging to the order Phthiraptera, complete their development on a human host. The life cycle consists of three distinct phases: egg (nit), nymph, and adult.
The egg is deposited by the female on hair shafts close to the scalp. Under optimal conditions—temperature around 30 °C and constant access to blood—the egg hatches after approximately 7–10 days.
Nymphs emerge as miniature, wingless insects. They undergo three molts before reaching maturity. Each molt requires about 3–4 days, resulting in a total nymphal period of roughly 9–12 days.
Adult lice are fully capable of feeding and reproduction. An adult female lays 5–8 eggs per day and can survive for 30 days on a host, provided a continuous blood supply. Males have a slightly shorter lifespan, averaging 20–25 days.
Key factors influencing longevity include:
- Host availability: Absence of a suitable host reduces survival to a few days.
- Temperature and humidity: Extreme conditions accelerate mortality; optimal range extends adult lifespan.
- Control measures: Chemical or mechanical interventions dramatically shorten life expectancy.
In summary, the complete life span from egg to death of an adult ranges from 20 days (minimum under adverse conditions) to about 40 days (maximum under ideal circumstances). Adult individuals typically persist for 2–5 weeks, while the entire developmental cycle occupies roughly 2–3 weeks.