Blood-feeding or sap-feeding arthropods, principally in the taxa Acarina and Insecta are major vectors of viruses of plants and vertebrates. The enormous associated literature suggests that the virus-vector interaction can be of distinct types, some adopted specifically by plant viruses and others by vertebrate viruses. Based on emblematic examples of poxviruses and orthomyxoviruses of vertebrates and of luteovirus, geminivirus, and nanovirus of plants, we here discuss the possibility that the current restriction of certain transmission modes to a given host type may simply reflect limited knowledge. Particularly, we question the absence of a specific relationship in some cases of 'mechanical' transmission of viruses of vertebrates and challenge the so-called 'circulative non-propagative' transmission as a discrete concept specific to plant viruses.