How do domestic lice appear? - briefly
Domestic lice originate when adult females deposit eggs (nits) on hair shafts, which hatch into nymphs that mature into reproducing adults within about a month. Infestations spread primarily through direct head‑to‑head contact or sharing items such as combs, hats, or bedding.
How do domestic lice appear? - in detail
Domestic lice infestations begin when adult female insects lay eggs, known as nits, on the hair shafts close to the scalp. The eggs hatch within 7–10 days, releasing nymphs that resemble miniature adults. Nymphs feed on blood three to four times a day, maturing through three molts over 9–12 days before becoming reproductive adults. An adult female can produce 6–10 eggs per day, allowing the population to expand rapidly if untreated.
The primary pathway for lice to enter a household is direct head‑to‑head contact with an infested person. Secondary routes include sharing personal items such as combs, hats, scarves, hair accessories, or bedding that have come into contact with live insects or viable nits. Lice survive only a few hours off the human host; therefore, transmission requires relatively recent contact with contaminated objects.
Environmental conditions influence the life cycle. Optimal temperature (30–32 °C) and humidity (50–70 %) accelerate egg development and nymph feeding. Cooler or drier settings prolong the incubation period and may reduce survival rates, but do not prevent infestation entirely.
Key stages of the infestation process:
- Egg deposition: Female attaches nits within 1 mm of the scalp using a cement-like substance.
- Hatching: Nits become viable larvae after 7–10 days.
- Nymphal growth: Three successive molts over 9–12 days, each requiring blood meals.
- Adult reproduction: Mature females resume oviposition, completing the cycle.
Effective control requires simultaneous removal of live insects, viable nits, and any contaminated personal items. Prompt treatment interrupts the reproductive cycle before the population reaches a level that causes noticeable symptoms.