The basis for transmission of arboviral agents from one host to another derives from the blood-feeding requirement of certain arthropods, mainly mosquitoes and ticks. Except for vertically and venereally transmitted agents, this act of feeding provides the circumstances for transmitting such pathogens and determines their degree of communicability. Successful hematophagy culminates in an intricate cascade of events. As a consequence of their interdependency, certain ixodid ticks insure perpetuation by ingesting massive quantities of blood, thereby producing extraordinary numbers of offspring; certain hematophagic flies exploit the reciprocal strategy by developing some eggs without taking any blood at all (autogeny). Vector species, however, tend to depend upon a close association with particular hosts, thereby optimizing feeding success and survival. It seems axiomatic that autogeny would invariably detract from the vectorial capacity of a vector population. Although this property helps the population to perpetuate in the absence of vertebrate hosts, autogenous individuals invariably experience fewer host-contacts during the course of their life.