See [page 72]
TIGER SWALLOWTAIL
Photographed from life
See [page 7]
THE HAMMOCK CATERPILLAR ON ITS HAMMOCK
The migrations thus considered are only exceptional occurrences. There is, however, a regularly recurring annual migration on the part of some butterflies which is also a phenomenon of extraordinary interest. The most notable example is that of the Monarch which apparently follows the birds southward every autumn and comes northward again in spring. There is much evidence to indicate that in some slight degree other butterflies have a similar habit, although the present observations are inadequate to determine to what extent this habit has become fixed in most of these species.