Abstract: The forewing forms of five species of migratory moths, Mythimna separata, Helicoverpa armigera, Cnaphalocrocis medinalis, Loxostege sticticalis and Agrotis ypsilon,and some species similar to them were analyzed numerically with their geometrical projections. Cluster analysis on their curvat ures showed that these migratory moths could be clustered to the same group and distinguished from their similar species, respectively. Discriminant analysis furt her demonstrated divergence of wing forms between migratory moths and non-migratory species. The forewing costal margin of migratory moths, especially the part from the middle of it to the wing-tip, is straighter than that of non-migratory species, and its outer area seems to be relatively wide. Such wing characteristics are more suitable for them to make a long-distance migration by airflow

Key words: migratory moths, similar species, wing-form, curvature, numerica