How do lice lay nits? - briefly
A female head louse uses her ovipositor to attach each egg (nit) to a hair shaft about 1 mm from the scalp, securing it with a protein‑rich cement. She deposits roughly five to eight nits daily, spacing them along the hair to maximize survival.
How do lice lay nits? - in detail
Head lice (Pediculus humanus capitis) reproduce by the female inserting each egg into the hair shaft close to the scalp. The adult female possesses a pair of specialized abdominal structures called oviscaptors, which grasp a single strand of hair. She then uses a proteinaceous adhesive secreted from her abdominal glands to anchor the egg to the fiber. The adhesive hardens within seconds, forming a firm bond that resists removal by normal combing.
The typical sequence is:
- Selection of site: The female prefers the warm, moist region behind the ears or at the nape of the neck, where the hair is dense.
- Attachment: She inserts the oviscapt into the hair at an angle of roughly 30‑45 degrees, positioning the egg about 1‑2 mm from the scalp surface.
- Secretion of glue: A viscous, melanin‑rich fluid is released, coating the base of the egg and the hair. The fluid polymerizes, creating a durable seal.
- Placement of egg: The egg, often called a nit, measures 0.8 mm in length and is positioned with the operculum (cap) facing outward. The female deposits 1‑3 eggs per minute, laying up to 10 per day and up to 100 over her lifespan.
- Incubation: The glued egg remains attached for 7‑10 days, during which the embryo develops. The operculum opens at hatching, allowing the nymph to emerge and immediately begin feeding.
Females continue this cycle throughout their 30‑day adult life, producing a new batch of eggs roughly every 2‑3 days. The adhesive composition, combined with the precise placement on the hair shaft, ensures that the eggs remain secure until the nymphs are ready to emerge.