Scaphytopius acutus(Say) transmitted a celery-infecting strain of aster-yellows virus from infected periwinkle (Vinca roseaL.) and aster (Callistephus chinensisNees) to periwinkle, aster, and ladino clover (Trifolium repensL.). It acquired the virus during feeds as short as 4 hours, and transmitted it during a 2-hour feeding period. The minimum incubation time for the virus in the insect was between 21 and 26 days. After an acquisition feed of 7 days and an incubation period of at least 30 days, 11 of 21 insects transmitted the virus to separate periwinkle test plants.