What does the harp tick look like?

What does the harp tick look like? - briefly

The harp tick is a minute, oval arachnid, typically reddish‑brown, with a dorsal surface marked by a pair of curved, harp‑shaped lines. Its legs are short and it attaches firmly to the host’s skin.

What does the harp tick look like? - in detail

The harp tick is a small arachnid, typically measuring 2 – 4 mm when unfed and expanding to 6 – 8 mm after engorgement. Its dorsum is a dark brown to black shield (scutum) that bears a distinctive pattern of fine, pale longitudinal lines resembling the strings of a harp. These lines are most visible on the anterior half of the shield and fade toward the posterior margin.

The body consists of two main sections: the capitulum (mouthparts) and the idiosoma (main body). The capitulum is short, with a pair of chelicerae and a prominent, forward‑projecting hypostome that appears as a dark, needle‑like structure. The legs are eight in total, each bearing long, slender segments covered with fine hairs (setae) that aid in attachment to hosts. The legs are uniformly dark, with the first pair slightly longer than the others, facilitating grasping.

Key visual markers include:

  • A smooth, rounded scutum with a harp‑like line pattern.
  • A small, rounded anal groove positioned posterior to the anus.
  • Palps that are shorter than the chelicerae, appearing as tiny, curved extensions near the mouth.
  • Absence of ornate ornamentation on the dorsal surface, distinguishing it from ornamental tick species.

When engorged, the tick’s abdomen swells, taking on a more oval shape, while the dorsal pattern becomes less distinct due to the stretched cuticle. The ventral side remains lighter, often pale beige, with visible spiracular plates near the posterior margin.

These characteristics together provide a reliable visual profile for identification in field or laboratory settings.