Ticks have a specialized sensory structure, called Haller's organ, that detects the presence of carbon dioxide, temperature, and humidity (Klompen and Oliver, 1993).
Haller's organ in the tick family Argasidae (Acari: Parasitiformes: Ixodida).
1975) and in Anactinotrichida, the well known Haller's Organ on tarsus I of Ixodida and Holothyrida and the telotarsal organ on tarsus I of Opilioacarida (summarized by Alberti & Coons 1999; Coons & Alberti 1999).
The tarsal pore organ of ricinuleids shows similarities to the proximal part of Haller's organ, the capsule, in Ixodida.
However, some main differences between Haller's organ of Ixodida and the tarsal organ of ricinuleids are evident.
The larva of a questing tick waves its front legs back and forth, checking the level of carbon dioxide in the air with its Haller's organs
. It also relies on pressure, heat, and movement sensors to identify a passing host.