Environmental scanning electron microscopy reveals detailed close-ups of the Haller’s organs of three tick species: Ixodes scapularis (Is), Amblyomma americanum (Aa), and Dermacentor variabilis (Dv). The Haller’s organ is a sensory pit on the foreleg used to detect heat and chemical odors emitted by potential hosts. “Landmarks” used in analysis of the organs are numbered. (Image originally published in Josek et al, 2017, Journal of Medical Entomology)