How do lice breed? - briefly
After mating, female head lice lay 5–10 eggs (nits) daily on the hair shaft, each hatching in 7–10 days. The emerging nymph matures into an adult within 9–12 days, allowing several generations each month.
How do lice breed? - in detail
Lice reproduce through a direct mating process that occurs on the host’s body. Adult females locate a male by detecting pheromones released by the male’s abdomen. Once a pair meets, the male mounts the female from behind, aligning his genital opening with hers. Copulation lasts a few minutes, during which sperm is transferred in a single act; lice do not store sperm for future fertilizations.
After insemination, the female begins oviposition within 24–48 hours. She uses her ovipositor to embed each egg (nit) firmly against the host’s hair shaft or skin surface, typically at a 45‑degree angle to ensure stability. Eggs measure 0.8 mm and are coated with a cement-like secretion that hardens within minutes, protecting the embryo from mechanical removal.
The female can lay 5–10 eggs per day, depending on species and environmental conditions, and may produce up to 100 eggs over her lifespan of about 30 days. Egg development proceeds through three embryonic stages:
- Cleavage phase (first 12 h): rapid cell division forms a blastoderm.
- Organogenesis (12–48 h): formation of head, thorax, and abdomen structures.
- Maturation (48–72 h): development of limbs, eyes, and respiratory spiracles.
Incubation completes after roughly 7–10 days, at which point the nymph hatches and immediately begins feeding on the host’s blood. Nymphs undergo three molts, each lasting 3–4 days, before reaching adult size and reproductive capability.
Temperature and humidity strongly influence the reproductive cycle. Optimal conditions (28–32 °C, 70–80 % relative humidity) accelerate egg development and increase hatch rates, whereas lower temperatures extend incubation and reduce fertility.
Male lice reach sexual maturity after the second molt and remain active throughout the female’s reproductive period, ensuring continuous mating opportunities. The entire lifecycle—from egg to reproductive adult—can be completed in as little as 10 days under ideal conditions, enabling rapid population expansion on a suitable host.