What do lice look like and what is their size? - briefly
Lice are tiny, wingless, dorsoventrally flattened insects with a blunt head, six legs and a color ranging from translucent gray to brown. Adult head lice measure about 2–4 mm, body lice about 3–5 mm, and their eggs (nits) are roughly 0.8 mm long.
What do lice look like and what is their size? - in detail
Lice are tiny, wing‑less insects that live on the bodies of mammals and birds. Their bodies are laterally flattened, facilitating movement through hair or feathers. The head, thorax and abdomen are clearly demarcated, each bearing a pair of short, sturdy legs equipped with clawed tarsi for gripping strands of hair.
Color ranges from translucent or pale gray in newly hatched individuals to a brownish‑gray in mature specimens. Head lice («Pediculus humanus capitis») typically appear dull gray, while body lice («Pediculus humanus humanus») may show a slightly darker hue. Pubic lice («Pthirus pubis») are often reddish‑brown, reflecting the presence of hemoglobin in their blood meals.
Key morphological features include:
- Six legs, each ending in a single claw; fore‑legs are adapted for grasping hair shafts.
- Antennae composed of five segments, used for sensory detection.
- A short, rounded head bearing compound eyes and mouthparts designed for piercing skin and sucking blood.
- Abdomen composed of several visible segments, often covered with fine setae that give a velvety texture.
Size measurements differ among species:
- Head lice: 2.3 – 3.5 mm in length (≈ 0.09 – 0.14 in).
- Body lice: 2.5 – 4.0 mm (≈ 0.10 – 0.16 in).
- Pubic lice: 1.5 – 2.0 mm (≈ 0.06 – 0.08 in).
Eggs, commonly called nits, measure about 0.5 mm (≈ 0.02 in) and are firmly attached to hair shafts near the scalp. Nymphs, the immature stages, are proportionally smaller than adults but retain the same body shape and coloration, maturing after three molts over a period of 7‑10 days.