How do lice species look? - briefly
Lice are tiny, wing‑less insects with a flattened, oval body 1–4 mm long, colored gray‑brown to reddish, and equipped with three clawed legs on each segment for clinging to hair or feathers. Head louse (Pediculus humanus capitis) is translucent and smaller, whereas body louse (Pediculus humanus humanus) is larger and darker.
How do lice species look? - in detail
Lice are small, wing‑less insects belonging to the order Phthiraptera. Body length ranges from 1 mm in the common head louse (Pediculus humanus capitis) to 5 mm in some larger avian species. Color varies between translucent, light brown, grayish or reddish tones, often matching the host’s hair or feathers.
The head louse exhibits an elongated, flattened body adapted for clinging to hair shafts. Antennae consist of five short segments, each bearing sensory cones. Legs end in sharply curved claws that grip the hair shaft near the base. The ventral surface bears a pair of spiracles for respiration, while the dorsal side carries sparse setae. Eggs (nits) are cemented to hair at a 45‑degree angle, appearing as oval, translucent capsules.
The body louse (Pediculus humanus humanus) differs by possessing a broader, more robust abdomen and a slightly larger size (2–4 mm). Legs are longer, allowing movement across clothing fibers rather than hair. The thorax bears prominent, hardened plates (sclerites) providing protection. Coloration is typically darker brown, sometimes with a reddish hue due to blood ingestion.
The pubic louse (Pthirus pubis)—commonly called the crab louse—has a broader, crab‑shaped body, measuring 1.5–2 mm. Its legs are markedly longer, with the first pair extending forward for grasping coarse hair. The body is dorsally convex and laterally flattened, giving a distinct “crab” silhouette. Color ranges from gray to dark brown.
Other lice species, such as feather lice (Columbicola spp.) and fur lice (Trichodectes spp.), display adaptations to their specific hosts. Feather lice possess a flattened, oval body with reduced legs, enabling movement between feather barbs. Fur lice have a more rounded abdomen and shorter legs, facilitating navigation through dense mammalian fur. Their coloration closely matches the host’s coat, providing camouflage.
In summary, lice morphology includes a compact, wing‑less form; segmented antennae; clawed legs specialized for attachment to hair, fur, or feathers; and coloration that blends with the host. Size, body shape, and leg length differentiate species and reflect their ecological niches.