What are lice larvae? - briefly
«Lice larvae», also known as nymphs, are the immature stage that hatches from the egg (nit) and resembles a smaller, wingless adult. They undergo three successive molts before reaching full maturity.
What are lice larvae? - in detail
Lice larvae, commonly referred to as nymphs, represent the immature stage that follows hatching from an egg (commonly called a nit). At emergence, the larva measures approximately 0.5 mm in length and lacks the fully developed thoracic and abdominal segmentation seen in adult specimens. The cuticle is soft, translucent, and bears limited setae, which gradually increase in number and size as molting progresses.
During the first instar, the nymph attaches to the host’s hair shaft or skin surface using a rudimentary claw. Feeding begins almost immediately; mouthparts are adapted for piercing and sucking blood, though the volume ingested is minimal compared to later stages. The larva relies on the host’s temperature and humidity to maintain metabolic activity.
Molting occurs three times, producing successive instars:
- First instar: soft body, limited mobility, primary feeding.
- Second instar: thicker cuticle, more pronounced setae, increased locomotion.
- Third instar: near‑adult morphology, robust claws, substantial blood intake.
Each molt is triggered by hormonal changes, primarily ecdysone, and takes 1–2 days under optimal conditions (temperature 30–32 °C, relative humidity 70–80 %). The complete development from egg to adult spans 7–10 days, after which the organism reaches reproductive maturity.
Morphologically, the nymph possesses a segmented abdomen, three pairs of legs, and a pair of antennae that become functional in the second instar. Respiratory spiracles open on the thorax and abdomen, allowing gas exchange while the insect remains attached to the host.
Detection relies on visual inspection of hair shafts for translucent nits near the scalp or skin surface, and for active nymphs moving slowly along hair or skin. Laboratory identification may involve microscopic examination of the cuticular pattern and measurement of body length to differentiate instars.
Control strategies target the nymphal stage because it is most vulnerable before cuticle hardening. Effective measures include:
- Application of pediculicidal agents that penetrate the soft cuticle.
- Mechanical removal of nits and attached nymphs using fine-toothed combs.
- Environmental interventions, such as washing bedding at temperatures above 60 °C to eliminate detached larvae.
Understanding the biology of lice larvae is essential for timely intervention, reducing infestation duration, and preventing progression to the adult stage, which possesses greater reproductive capacity.