For the grub of the bee, the hornet, and the wasp, whilst it is young, takes food and is seen to produce excrement; but when it has passed from the grub shape to its defined form and become what is termed a pupa, it ceases to take food and to void excrement, and remains tightly wrapped up and motionless until it has reached its full size, when it breaks the formation with which the cell is closed, and issues forth.