How does a louse appear on eggs? - briefly
Female lice cement their eggs to hair shafts near the scalp, creating small, oval nits that appear as white or yellowish shells attached to each strand.
How does a louse appear on eggs? - in detail
Lice become associated with eggs through a specific reproductive behavior. The adult female deposits her ova on a suitable substrate, typically hair shafts in humans or feathers in birds. Each egg is secured by a proteinaceous cement that hardens within minutes, creating a firm attachment that resists removal by routine grooming.
The attachment process involves three stages:
- Cement secretion – the female’s accessory glands produce a viscous adhesive that spreads over the base of the egg.
- Polymerisation – exposure to ambient temperature triggers rapid hardening, forming a resilient bond.
- Orientation – the egg is positioned at an angle of 30–45 ° to the host filament, optimizing access to oxygen and minimizing dislodgement.
Incubation periods vary with species and environmental conditions. For Pediculus humanus capitis, development lasts 7–10 days at 30 °C and 70 % relative humidity. During this time, the egg remains immobile; metabolic activity is limited to embryonic growth.
Hatching produces a nymph that immediately seeks a feeding site on the host. The cycle repeats as the nymph matures into a reproductive adult within 9–12 days, after which further eggs are laid on the same host filament.
Factors influencing the initial appearance of lice on eggs include:
- Host density – close contact among individuals facilitates transfer of gravid females.
- Temperature and humidity – conditions that support cement polymerisation and embryonic development.
- Substrate integrity – intact hair or feather shafts provide the necessary surface for cement adhesion.
Detection relies on visual identification of the cemented ova, often described as translucent ovoids measuring 0.8 mm in length. Microscopic examination reveals a characteristic operculum at one pole, indicating the site of hatching.
Control strategies target the cement bond. Chemical agents that dissolve the adhesive or physical methods that detach the egg from the substrate effectively reduce the presence of lice on eggs.