Abstract: An investigation of long distance migration of the greenbug Schizaphis graminum (Rond ani) was conducted in Ningxia from 1971 to 1987, and the following relevant evidences have been obtained. When the immigration peak of the greenbug alates to spring wheat fields occurs, emergence of Mates from tlie local overwintering population in grassplots has ended; Mates carrying virus (BYDV) were captured in the fields in Ningxia m early spring, whereas none of the local overwintering aphids carried the virus; and incidence of BYDV in Ningxia in spring correlated closely with the abundance of the overwintering greenbug in south-easternwinter wheat region, but not correlated with Ningxia overwintering population abundance. It is concluded for the first time that there is a long distance migration of the aphid and the immigrant aphids are the main sources of the greenbug inNingxia in spring time. Regions which may be the source areas for the immigrant aphids to Ningxia are speculated. Ecological implications of the immigrant aphids, function of the southeasterly wind and the relevant problems to be studied in future are discussed.

Key words: Schizaphis graminum, migration