Southern Migration of Butterflies

Abstract

Not in many years has the southern migration of the Great Southern White, or Gulf Butterfly (Pieris monuste L.), been quite so great or noticeable as during the early part of June of this year (1923). Their numbers along the waterways of the east coast of Florida, especially along the Halifax and Indian Rivers, were so great that the radiators of automobiles driving north and south became thoroughly plastered with them. The migration is constantly southward and one wonders where this tremendous army comes from. It seems that they are first noted in large numbers in the vicinity of Titusville and as one travels southward their numbers seem to increase until they reach unlimited millions between Fort Pierce and Stewart, with an apparent increase in numbers as they advance southward. Always they are noted as flying thickest along the edges of the water, such as the two rivers above mentioned, Lake Worth, the East Coast Canal and Biscayne Bay. There they apparently leave the mainland and follow the Gulf Stream to no one knows where. It is not unlikely that these butterflies begin to make up the bulk of their army in such states as the Carolinas and Georgia, foil they have been reported in the vicinity of Jacksonville, Florida, on their journey south. It is observed that numbers of these butterflies occur some three to five miles west of the inland waterways and are always flying eastward, apparently for the purpose of joining the main army in the southward flight. It is not unlikely that many of these butterflies breed and hatch in certain portions of the swamp lands and Everglades of the interior; also in farms and fields where cabbages and collards are grown. These butterflies, upon reaching maturity, apparently follow instictively the eastward 8