The vector competence of a Kentucky strain of Aedes albopictus was assessed for a newly recognized Bunyavirus isolated from Ae. albopictus collected in Potosi, Missouri. Females are susceptible to peroral infection and 44.7% became infected after ingesting about 15 Vero cell plaque-forming units (PFU) of virus. Virus replicated and reached average titers of 10(5.4)-10(6.0) PFU/mosquito by day 7 postfeeding. Fourteen (40%) of 35 females tested in an in vitro virus transmission experiment were infected, and 3 (21.4%) of the infected females transmitted virus. There was no evidence of vertical transmission among 1,196 progeny of a group of mothers exposed to infection perorally or among 6,635 progeny of mothers infected by parenteral inoculation. The absence or infrequency of vertical transmission suggests that the virus was not introduced into Missouri via infected Ae. albopictus eggs. Nonetheless, Ae. albopictus is a competent vector of this virus and we provide the first experimental evidence for incriminating Ae. albopictus as a vector in a natural arbovirus transmission cycle in the United States.