What do a forest tick and an encephalitic tick look like? - briefly
Both are small, dark brown arachnids about 2–5 mm long; the forest tick (Ixodes ricinus) has a rounded, scutum‑covered back with a uniformly reddish‑brown underside, whereas the encephalitic tick (Ixodes persulcatus) is similar in size but often displays a slightly lighter, mottled dorsal pattern and a more distinct longitudinal line.
What do a forest tick and an encephalitic tick look like? - in detail
The forest tick, commonly identified as Ixodes ricinus, measures 2–3 mm when unfed and expands to 5–8 mm after engorgement. Its body is oval, dark brown to reddish‑brown, with a smooth, hexagonal scutum covering the dorsal surface of the male and the anterior half of the female. The scutum lacks distinct patterns, appearing uniformly pigmented. The ventral side bears a lighter, creamy‑white opisthosoma. Six legs emerge from the anterior region; each leg consists of a long, slender trochanter, a short femur, a robust patella, a short tibia, and a small tarsus ending in a claw. The mouthparts (capitulum) are located ventrally, with chelicerae and a short, straight hypostome bearing rows of backward‑pointing teeth.
The encephalitic tick, typically Ixodes persulcatus, shares the general Ixodes morphology but differs in several diagnostic traits. Unfed individuals are 2–3 mm in length, similar in size to the forest species, yet the dorsal shield exhibits a darker, almost black coloration with subtle, irregular mottling rather than a uniform hue. The scutum is slightly broader relative to body width, and the posterior margin often shows a faint, pale fringe. The legs are proportionally longer, giving the tick a more elongated appearance when viewed laterally. The capitulum is more pronounced, with a hypostome bearing deeper, more widely spaced denticles. Additionally, I. persulcatus possesses distinct festoons—small rectangular cuticular plates—along the posterior edge of the body, which are more conspicuous than in I. ricinus.
Key distinguishing characteristics:
- Scutum coloration: uniform dark brown (forest) vs. darker, mottled with pale fringe (encephalitic).
- Body outline: compact oval (forest) vs. slightly elongated, broader scutum (encephalitic).
- Leg length: relatively shorter (forest) vs. noticeably longer (encephalitic).
- Hypostome dentition: modest, evenly spaced (forest) vs. deeper, wider spaced (encephalitic).
- Festoons: less evident (forest) vs. prominent rectangular plates (encephalitic).
Both species exhibit the typical three‑host life cycle, undergoing larval, nymphal, and adult stages, each stage capable of feeding on a range of vertebrate hosts. Accurate visual identification relies on careful observation of the scutum pattern, leg proportion, and hypostome structure, which together provide reliable differentiation between the two medically relevant ticks.