The caterpillars that hibernate when full grown may be grouped in a way somewhat similar to those which are half grown. Many species simply find such shelter as they may at or near the soil surface. The Clouded Sulphur is a good example of these. Others pass the winter in individual shelters made from a leaf or blade. Several of the larger Skippers are good examples of this condition. So far as I know none of our species pass the winter in colonial shelters when full grown. It would be natural to suppose that the great majority of butterflies would be likely to hibernate in the chrysalis state. Here is a quiet stage in which the insect is unable to move about or to take any food, in which it seems entirely dormant and as a rule is fairly well hidden from the view of enemies. We find, however, that only a rather small proportion of our butterflies has chosen this stage for survival through the winter. The most conspicuous examples are the Swallowtails, nearly all of which hibernate in the chrysalis stage. Other examples are the various Whites, the Orange-tips, and isolated species like the Wanderer, and the Spring Azure and the American Copper. Practically all the butterflies that pass the winter as chrysalids have a silken loop running around near the middle of the body which helps to hold them securely through the long winter months. Apparently none of those chrysalids which hang straight downward are able to survive the winter. An adult butterfly seems a fragile creature to endure the long cold months of arctic regions. Yet many of our most beautiful species habitually hibernate as adults, finding shelter in such situations as hollow trees, the crevices in rocks, the openings beneath loose bark or even the outer bark on the under side of a large branch. It is significant that most of the adult-wintering Angle-wings are northern rather than southern species, some of them being found in arctic regions practically around the world. One of the few southern forms that hibernates as an adult is the Goatweed Emperor. These examples are all cases of true hibernation in a lethargic condition. There are certain butterflies, however, which pass the winter as adults that remain active during this period. Obviously this is impossible in latitudes where the winter is severe, and it involves migration to a warmer climate. The one notable illustration of this is the Monarch butterfly which apparently flies southward to the Gulf states at least and there remains until spring, when individuals come north again. The southward migration may be begun in Canada when the butterflies gather together in enormous flocks that remind one of the gathering of the clans with the migrating birds. This is one of the least understood of insect activities but it has been observed so often and over so long a period of years that there seems to be no questioning the general habit.