In the course of the transmission experiment carried out in the present work, the author pointed out a Rhopalosiphum  padi  (L.) transmitting the virus causing barley yellow dwarf  disease (BYDV) from infect wheat  plants to celery plants and from infected celery plants to healthy ones. It plays an important role in spreading the barley yellow dwarf virus in wheat cultivations in Sharkia Governorate, Egypt. The results of insect transmission experiment could be summarized as follows: The acquisition threshold feeding periods ranged between 1 hr and 24 hr. Incubation periods in insects ranged between 48 - 73 hr. , while in the host plants were 18 to 22 days in celery plants.