What do lice and ticks look like? - briefly
Lice are tiny, wing‑less insects 2–4 mm long, featuring a flattened, elongated body, six legs, and a gray‑white coloration that adheres closely to hair shafts. Ticks are arachnids ranging from 2 mm to several centimeters when engorged, possessing a rounded, reddish‑brown body, eight legs, and a smooth or textured appearance on the skin.
What do lice and ticks look like? - in detail
Lice are tiny, wing‑less insects measuring 2–4 mm in length. Their bodies consist of a head, thorax, and abdomen, each covered by a smooth, flattened exoskeleton. The head bears a pair of antennae about 0.3 mm long, compound eyes (absent in some species), and chewing mouthparts adapted for feeding on blood or skin debris. Three pairs of legs emerge from the thorax; each leg ends in claw‑like tarsi that allow firm attachment to hair shafts. Coloration varies by species: head lice are typically gray‑white, while body lice appear darker, ranging from brown to reddish‑brown. The abdomen may show subtle segmentation but lacks prominent markings.
Ticks are arachnids, larger than lice, with adult sizes from 2 mm (unfed) to 10 mm or more after engorgement. Their body divides into a dorsal shield (scutum) and a ventral region. Hard ticks (family Ixodidae) possess a rigid scutum covering the entire dorsal surface in males and only the anterior portion in females; soft ticks (family Argasidae) lack a scutum, presenting a leathery, wrinkled dorsum. Mouthparts form a protruding capitulum equipped with chelicerae and a hypostome bearing backward‑pointing barbs for secure attachment to host tissue. Six legs, each ending in small claws, support locomotion. Color ranges from reddish‑brown in many species to darker hues in others, often with visible patterns of spots or stripes on the scutum. Engorged females become noticeably distended, their bodies expanding to accommodate several times their unfed weight.
Key visual distinctions:
- Size: lice 2–4 mm, ticks 2 mm–10 mm (varies with feeding status).
- Body plan: insects with three distinct regions vs. arachnids with two main regions.
- Legs: three pairs in lice, four pairs in ticks.
- Exoskeleton: smooth, flattened in lice; scutum present in hard ticks, absent in soft ticks.
- Mouthparts: chewing mandibles in lice; piercing‑sucking capitulum in ticks.