What types of lice are there and how do they look? - briefly
Humans host three primary lice species: head lice (Pediculus humanus capitis) and body lice (Pediculus humanus corporis), which are slender, gray‑brown insects 2–4 mm long with six legs, and pubic lice (Pthirus pubis), a broader, crab‑shaped parasite about 1–2 mm in size. Head and body lice possess elongated bodies and clear wings, whereas pubic lice have a flattened, rounded abdomen and a noticeably wider body shape.
What types of lice are there and how do they look? - in detail
Lice are obligate ectoparasites that specialize in different host regions. Three species infest humans, each with distinct morphology and habitat.
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Head louse (Pediculus humanus capitis) – Adult length 2–3 mm, flattened, oval body, translucent to grayish‑brown. Antennae are short, legs equipped with claws that grasp hair shafts. Eggs (nits) are oval, 0.8 mm, firmly cemented to the base of hair shafts, appearing as white or yellowish ovals.
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Body louse (Pediculus humanus humanus) – Slightly larger, 3–4 mm, similar oval shape, but coloration ranges from light brown to reddish‑brown. Lacks the ability to cling to hair; instead, it clings to clothing fibers and moves to the skin to feed. Nits are larger than head‑lice eggs, attached to seams of garments rather than hair.
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Pubic louse (Pthirus pubis) – Commonly called crab louse, 1.5–2 mm in length, broader and more rounded body resembling a crab. Legs are stout and extend laterally, giving a crab‑like appearance. Color varies from gray to brown. Nits are attached to coarse body hair, appearing as tiny, translucent ovals near the hair base.
Other lice affect animals but are not considered human parasites. Their appearance follows similar patterns: small, wingless insects with specialized claws matching the host’s hair or feather structure. Size typically ranges from 0.5 to 5 mm, coloration from translucent to dark brown, and bodies are dorsoventrally flattened to facilitate movement through hair or fur. Eggs are uniformly oval and glued to host substrates with a cement‑like secretion.