Investigation on long distance migration of grain aphid (Macrosiphum avenae (Fabr.)) in Ningxia.

The investigation was conducted in Ningxia in 1972-1978. Evidences of long distance mi-gration of the grain aphid Macrosiphum avenae (Fabr.) are provided by the presence of alate form of the grain aphid before emergence of the local winged nymph, the appearance of the summer form aphids In spring which can only occur at the ear stage of wheat, the capture of the winged aphids in Liupanshan Mountain Meteorological Station in the freezing season, the presence of the winged aphids in different geography-ecological regions at the same time and the ratio of more than 98.8% of immigrant winged aplude in the spring population. It is ron-cluded for the firsf time that there is a long distance nugration of the aphid and the immigrant aphids are the main sources of the grain aphid in Ningxia in spring time .Regions possibly supplying immigrant aphids to Ningxia and the relevant problems to be studied in future are discussed.