Viruses from each genus of Bunyaviridae have preferential relationships to the arthropods of only one or two families, i.e. Bunyavirus to mosquitoes (Culicidae), Phlebovirus to sand flies (Psychodidae) and mosquitoes, Uukuvirus and Nairovirus to ticks (Ixodidae and Argasidae). An exception is genus Hantavirus not proven to be transmitted by vectors. Within the Bunyavirus genus 16 serogroups have been recognized on the basis of their antigenic relationship. Based on isolations from the nature each serogroup is preferentially linked with arthropod species (mostly mosquitoes) of one, or two genera. For 8 out of 16 serogroups Culex mosquitoes are the main insect vectors. Two serogroups are linked with Aedes mosquitoes, three with Anopheles mosquitoes. Aedeomyia mosquitoes, Culicoides bitting miges and Hyalomma ticks are vectors of one serogroup each. Evolutionary trends within the genus Bunyavirus and within the family Bunyaviridae can be recognized based on relationships of bunyaviruses to their arthropod vectors.