A number of butterfly species have the habit of migration, perhaps the most noted of which is Pyrameis cardui, commonly known as the Painted Lady. This designation is particularly fitting on account of the gay coloration and intricate pattern of this interesting butterfly. It is a widely distributed insect occurring in most portions of the globe. Much has been written concerning its habits and life history. There are, however, several points still to be determined, some of which concern the origin of the migratory swarms that have been recorded. For this reason the author has undertaken a comprehensive study of the species.