What does the largest tick look like? - briefly
The largest tick, the Australian paralysis tick (Ixodes holocyclus), can swell to roughly 12–15 mm after feeding, forming a distended, brown‑gray oval body with clearly visible legs. Its engorged appearance resembles a small, soft‑shelled berry.
What does the largest tick look like? - in detail
The largest known tick is the species Haemaphysalis longicornis (Asian long‑horned tick) when it reaches extreme sizes, though the record‑holding individual belongs to Dermacentor variabilis that can attain a length of about 12 mm and a width of 5 mm after engorgement. Its body is oval, dark brown to reddish‑black, with a hardened dorsal shield (scutum) covering the entire back in males and the anterior half in females. The scutum bears fine punctate patterns that give a textured appearance. When fully fed, the abdomen expands dramatically, becoming balloon‑like and turning a pale grayish hue, while the legs remain relatively short and stout, each ending in hooked claws for attachment. The mouthparts—particularly the chelicerae—are elongated, allowing deep penetration into host tissue. Internally, the engorged tick contains a volume of blood up to 200 times its unfed weight, visible as a translucent, gelatinous mass beneath the cuticle. The overall silhouette resembles a flattened, rounded capsule that swells markedly during feeding, distinguishing it from smaller species whose bodies remain comparatively compact.