What do lice on the body look like? - briefly
Adult body lice measure 2–4 mm, are gray‑brown, flattened, and have six legs; nymphs are smaller, paler versions of the same shape.
What do lice on the body look like? - in detail
Human lice are small, wing‑less insects that range from 2 to 4 mm in length as adults. Their bodies are flattened laterally, allowing them to move easily through hair shafts or clothing fibers. The exoskeleton is a smooth, translucent to grayish‑brown cuticle; in well‑fed individuals it may appear slightly darker due to the presence of digested blood.
The head is small, round, and bears a pair of short, beaded antennae about one‑third the body length. Each antenna consists of five segments, the terminal segment often bearing a tiny sensory bristle. Mouthparts are adapted for piercing skin and sucking blood; they consist of a slender, elongated proboscis that retracts when not feeding.
Six legs emerge from the thorax, each bearing clawed tarsi that grip hair or fabric. The legs are relatively long compared to the body, giving the insect a hopping appearance. The abdomen is segmented, with visible dorsal plates (tergites) that may show a faint pattern of pale lines in some specimens.
Sexual dimorphism is subtle. Females are slightly larger and have a more rounded abdomen to accommodate egg production. Males possess a broader thorax and may display a small, curved genital shield on the ventral side.
Nymphs resemble miniature adults but lack fully developed wings (which lice never develop) and have a lighter, almost transparent coloration. They molt three times before reaching maturity, each stage increasing in size by roughly 0.5 mm.
Key visual identifiers:
- Size: 2–4 mm (adult), 1–2 mm (nymph)
- Color: translucent to gray‑brown; darker after a blood meal
- Body shape: flattened, oval, smooth cuticle
- Head: small, round, with five‑segmented antennae
- Legs: six, ending in clawed tarsi for gripping
- Abdomen: segmented with faint dorsal lines; females larger, rounded
- Eggs (nits): oval, 0.8 mm, firmly attached to hair shafts or fibers near the scalp or seam line, with a characteristic operculum at one end
These characteristics allow precise identification of lice on the human body and differentiate them from other ectoparasites.