38 INSECT BEHAVIOR 



the battle color. Later the craft appears once more upon the water. 

 Altered tremendously, the old hulk still serves the fundamental pur- 

 pose. It is much the same with the insect. The larval wasp is 

 commandeered by nature. She must be fitted to meet new conditions 

 in order to perpetuate her race. Thus the task devolves upon his- 

 tolysis, the wrecker, and histogenesis, the builder. 



During the period of larval growth, from the time it hatches 

 until the provisions in the cell are entirely consumed, the grub rids 

 itself of no waste matter whatever. Unlike the larva of the butterfly 

 that excretes every few minutes as it eats during the days of its worm 

 life, the young wasp waits until its stores are gone and its cocoon 

 spun before passing off the waste of its five-day gorge. Even then it 

 waits another day before finally depositing it in a single mass at the 

 lower pole of the cocoon. A few days later pupation takes place. 



In the days which pass, between excretion and pupation, no foreign 

 matter appears within the cocoon. The insect is motionless: its 

 cradle, save for the hardened mass at one end, is scrupulously clean. 

 I remove this mass, float it out in a little water and subject it to a 

 thorough inspection under the microscope. It contains bits of chitin, 

 hairs and fragments of claws, all, however, fragments of the deceased 

 roaches. There is nothing unusual in the array, no bits of larval 

 anatomy, no fragments of the grub itself. What then becomes of the 

 material that histolysis is supposed to dispoil? Are the skin cells all 

 of the grub's anatomy that serve to build the wasp? 



I cut open the body of a grub, three days after the cocoon is spun. 

 The greater part of it runs through the incision as a smooth, pasty 

 liquid, amorphous in every way. At eight days, I open a second 

 grub. Now it is partly paste, but mostly wasp ! 



The laborers of histolysis are not altogether wreckers then. They 

 are concerned more with tearing down the old timbers, removing the 

 rusty nails, puttying the holes and handing them back to the equally 



