What do lice and their larvae look like? - briefly
Adult lice are tiny, wing‑less insects about 2–4 mm long, flattened, gray‑brown, with six legs and a head that extends slightly forward. Their nymphs look like miniature, initially translucent versions of the adults and darken after each of the three molts.
What do lice and their larvae look like? - in detail
Lice are small, wing‑less insects ranging from 1 mm to 4 mm in length, depending on species. Their bodies are laterally flattened, facilitating movement through hair or feathers. The exoskeleton is sclerotized, giving a glossy, brown‑to‑gray coloration; some species display a faint reddish hue from ingested blood. Heads are proportionally large, bearing a pair of short antennae and compound eyes. Mouthparts are adapted for piercing and sucking, with a curved, needle‑like stylet that penetrates the host’s skin. Legs end in clawed tarsi that grip individual hairs, and each leg bears three pairs of spines for anchorage.
The immature stages, called nymphs, resemble miniature adults but lack fully developed reproductive organs. Nymphs progress through three molts:
- First instar: approximately 0.5 mm long, translucent to pale yellow, with underdeveloped claws and reduced sclerotization.
- Second instar: 0.8–1 mm, more opaque, body becomes darker as cuticle thickens; claws improve, allowing stronger attachment.
- Third instar: 1–1.5 mm, coloration close to adult, fully functional claws, but still unable to lay eggs.
All stages possess a dorsal thorax and abdomen covered in fine setae, which aid in sensory perception. The ventral surface bears a pair of spiracles for respiration. Egg shells (nits) are oval, 0.5 mm long, firmly cemented to hair shafts; they appear white or yellowish until hatching, when nymphs emerge and immediately seek a feeding site.
Overall, the visual distinction between adult lice and their larvae lies in size, degree of sclerotization, and coloration intensity, while structural features such as claws, antennae, and mouthparts remain consistent throughout development.