The Common Green Darner, Anax junius, is one of the few North American dragonflies that performs annual long-distance migrations. Mature adults move north in spring and breed during the summer. The new generation emerges in late summer and flies south. At times migrants are seen in large numbers, especially on the Atlantic coast but also in the Great Lakes. Occasionally they are found far out at sea off southern California in fall. They are also commonly seen from oil platforms in the Gulf of Mexico.