Distribution of the alate virginopara of Aulacorthum solani in two kidney bean fields was investigated in the Tokachi district of Hokkaido. The fields surveyed were located near a large-scale grassland of public rearing pasture. The migration period of A. solani alates concentrates from mid June to early July in the Tokachi district. Because A. solani cannot grow on kidney beans, the distribution of alates in both fields indicates the aspect of infestation flight of alates which migrated from hibernaculum. Alates tended to alight on the edges of both fields, and the distribution was not influenced by surrounding vegetation. It was supposed that A. solani alates, which migrated from hibernaculum, invaded the field by a high-altitude flight, and were attracted by the edges as the way of alighting behavior due to the contrast between the color of the fields and surrounding area.