The ladybeetle Coccinella septempunctata L. is a major natural enemy of aphides, the aphid is a serious pest of agriculture and forestry. Sudden increase in the number of the beetles and then their aggregation occurred in the vast land at seaside of the Gulf of the Bohai sea and the Yellow sea of China. Detailed analysis showed that these beetles which appeared at seaside most probably did not occur in the local area, in which they migrated in large quantity from elsewhere. The observation of last eight yea...