From a drawing by Mary E. Walker
See [page 76]
ZEBRA SWALLOWTAILS
Visiting blossoming branches of the pawpaw tree. (Reduced)
See [pages 97-115]
SOME OF THE TRIBE OF YELLOWS
upper surfaces at left; under surfaces at right
(1) The Black-bordered Yellow—male; (2) the Clouded Sulphur—male;
(3) the Orange Sulphur—female; (4) the Dog's-head—male
These caterpillars continue to feed in this manner for about a week, remaining side by side when feeding, and marching in processions from one leaf to another as the food supply is exhausted. Wherever they go, each spins a silken thread on the surface traversed, so that the combination of all the threads makes a sort of carpet that serves as a foothold for the caterpillars. At the end of the week they moult or cast their skins, a process in which the skin of each larva splits open along the back, and the larva crawls out covered with a new skin that had been formed beneath the old one. This new skin stretches somewhat after the caterpillar emerges, so that the insect is able to increase considerably in size. At the period of moulting, the caterpillars remain quiet for a short time, but they soon become active again and begin feeding with increased voracity.