What are lice eggs? - briefly
Lice eggs, often referred to as nits, are tiny, oval, translucent embryos that attach firmly to individual hair strands close to the scalp. They incubate for roughly 7–10 days before hatching into mobile nymphs that commence blood‑feeding.
What are lice eggs? - in detail
Lice ova, often referred to as nits, are the embryonic stage of head‑lice (Pediculus humanus capitis). Each egg is a tiny, oval capsule measuring about 0.8 mm in length and 0.3 mm in width. The shell, composed of a hard, translucent protein called chorion, protects the developing embryo from external forces and desiccation.
The female louse deposits eggs singly onto the hair shaft, typically within 1 cm of the scalp where temperature and humidity are optimal for development. Attachment occurs via a cementing substance secreted from the louse’s abdominal glands; this glue hardens within seconds, anchoring the nit firmly to the hair. The cement is resistant to water and most shampoos, which is why manual removal often requires a fine‑toothed comb.
Development proceeds through three distinct phases:
- Embryogenesis (first 5–7 days): The embryo undergoes cellular division, forming a rudimentary head, thorax, and abdomen. Respiratory spiracles open, allowing gas exchange through the porous shell.
- Maturation (days 8–9): Internal structures differentiate; the future louse begins to acquire its characteristic body segmentation and appendages.
- Hatching (day 10): Enzymatic activity weakens the chorion, and the nymph emerges, immediately seeking a blood meal to continue its life cycle.
Temperature, humidity, and host grooming behavior influence hatching time. At 30 °C and 70 % relative humidity, hatching may occur as early as nine days; lower temperatures extend the incubation period to up to two weeks.
Identification relies on visual cues: nits appear as tiny, oval, white or yellowish dots firmly attached to hair. They differ from dandruff or hair casts by their immobility and the angle of attachment—typically at a 45‑degree tilt relative to the hair shaft. Under magnification, the operculum (a small cap at one end) may be seen, indicating the site where the nymph will emerge.
Management strategies focus on disrupting the cemented attachment or preventing hatching. Effective measures include:
- Mechanical removal: Use a fine‑toothed nit comb on wet, conditioned hair; repeat every 2–3 days for at least two weeks.
- Chemical treatment: Apply pediculicidal agents containing permethrin, pyrethrins, or dimethicone; follow label instructions to ensure coverage of the entire scalp.
- Environmental control: Wash bedding, clothing, and personal items in hot water (≥ 60 °C) or seal them in a plastic bag for 48 hours to kill any detached eggs.
Understanding the morphology, attachment mechanism, and developmental timeline of lice eggs is essential for accurate diagnosis and effective eradication.