Ornithodoros hermsi is a soft-bodied tick of the family Argasidae. It is one of the smallest ticks of the species Ornithodoros.[2] Females are larger than the males.[3] O. hermsi has a multihost lifecycle,[1] and some females have been observed to live four years without any blood meals.[3] They are parasites of rodents and other small mammals. The most favored host is the western chipmunk, Eutamias spp.