Haller's organ

Haller's organ marked by arrows

Haller's organ is a complex sensory organ that ticks bear. The organ detects hosts – which the tick, being an obligate parasite, must find in order to survive – via olfaction and the sensing of humidity, temperature, and carbon dioxide. Haller's organ is a minute cavity at the terminal segment of the first pair of a tick's legs (not the pedipalps). Each one is composed of a pit and a capsule, which contain sensory setae.

References

• Anne Baker. "Taxonomy". Ixodes ricinus. Natural History Museum. Retrieved October 10, 2011.
• G. H. F. Nuttall, W. F. Cooper & L. E. Robinson (1908). "On the structure of "Haller's organ" in the Ixodoidea". Parasitology 1 (3): 238–242. doi:10.1017/S0031182000003486.