What do ticks look like when they appear? - briefly
Ticks are tiny arachnids, usually 2–5 mm long, with a flattened, oval body and a reddish‑brown or dark brown color; before feeding they appear smooth and flat, and after attaching they swell into a rounded, grayish‑white, engorged form.
What do ticks look like when they appear? - in detail
Ticks are small, arachnid parasites that become noticeable when they first attach to a host. Their appearance varies with life stage, species, and feeding status.
An unfed larva measures 0.5–1 mm, appears translucent or pale yellow, and has six legs. Its body is smooth, lacking a hard shield. A nymph is larger, 1.5–2 mm, often reddish‑brown, and bears eight legs. The dorsal surface may show a faint scutum (a shield‑like plate) that is less distinct than in adults.
Adult ticks range from 2 mm (female) to 5 mm (male) in length when unfed. Typical coloration includes brown, reddish‑brown, or gray, with a clearly defined scutum on the dorsal side of the female and a narrower one on the male. The scutum’s texture is hard and glossy, often marked with fine punctuations or patterns unique to species. Eyes are absent; instead, a pair of sensory organs (Haller’s organs) is located on the forelegs. The mouthparts—chelicerae and a hypostome—are visible as a small, backward‑pointing structure at the front of the body.
When feeding, ticks expand dramatically. An unfed female can swell to 10–12 mm, becoming soft, spherical, and grayish‑white. The scutum remains unchanged in size, giving the engorged tick a distinctive “two‑tone” appearance: a small, hardened shield on a much larger, soft abdomen. The legs become elongated and more visible, and the hypostome protrudes prominently.
Key visual identifiers:
- Size: 0.5 mm (larva) to >10 mm (engorged adult female).
- Leg count: six (larva), eight (nymph and adult).
- Dorsal shield: absent in larvae, faint in nymphs, prominent in adults.
- Color: translucent/pale (larva), reddish‑brown (nymph), brown/gray (adult).
- Shape when engorged: soft, rounded body with a small hard shield.
These characteristics enable reliable identification of ticks at the moment they are first observed on skin, clothing, or the environment.