What do lice, nits, and fleas look like? - briefly
Lice are tiny, wing‑less insects 2–4 mm long, gray‑brown, with a laterally flattened body and six legs that cling to hair or clothing. Their eggs, called nits, appear as tiny, oval, white‑to‑tan capsules about 0.8 mm attached to the hair shaft, while fleas are slightly larger, 1.5–3.5 mm, dark brown, laterally compressed and equipped with powerful hind legs for jumping.
What do lice, nits, and fleas look like? - in detail
Lice, their eggs, and fleas each possess distinctive morphological traits that enable reliable identification.
Head lice (Pediculus humanus capitis) are small, wingless insects measuring 2–3 mm in length. Their bodies are flattened laterally, facilitating movement through hair shafts. Color varies from gray‑white to brown, often matching the host’s scalp. Six legs end in claw‑like tarsi, each bearing a pair of curved hooks used to grasp hair. Antennae are short, composed of five segments, and eyes are reduced to simple ocelli.
Nits, the eggs of head lice, are oval, about 0.8 mm long, and firmly attached to the base of hair strands by a cement‑like secretion. Their shells are translucent at first, becoming more opaque and yellow‑brown as embryos develop. The operculum, a small cap at one pole, can be seen as a faint white spot. Nits are positioned within 1 cm of the scalp, where temperature sustains embryogenesis.
Fleas (Siphonaptera), commonly the cat or dog flea, measure 2–4 mm when unfed and up to 5 mm after a blood meal. Their bodies are laterally compressed, giving a “jewel‑like” appearance. Color ranges from reddish‑brown to dark brown, often with a glossy sheen. The head is small, lacking eyes, and bears long, serrated antennae. Six strong legs end in spines that allow rapid jumping; the hind legs are especially enlarged. The abdomen expands noticeably after feeding, becoming distended and paler.
Key visual differences:
- Size: lice ≈ 2–3 mm; nits ≈ 0.8 mm; fleas ≈ 2–5 mm.
- Body shape: lice flattened laterally; fleas laterally compressed and more robust.
- Attachment: nits cemented to hair; fleas free‑living, capable of jumping.
- Color progression: lice variable; nits shift from translucent to yellow‑brown; fleas darken after feeding.
These characteristics provide a basis for accurate distinction during examination.