Cimex is a genus of insects in the family Cimicidae.[1] Cimex species are ectoparasites that typically feed on the blood of birds and mammals. Two species, Cimex lectularius and Cimex hemipterus, are known as bed bugs and frequently feed on humans, although other species may parasitize humans opportunistically.[2] Species that primarily parasitize bats are known as bat bugs.