412 TROPICAL WILD LIFE IN BRITISH GUIANA 



the truth she might store her nest with tlie ever ahiindant 

 spider in years of eaterpilhir scareity. 



Furtlier, the experiment points out that in the wasp's 

 vietim, ])aralysis may be brouojit about by tlie thrust of the 

 dart unaided by its poison. It is the stabbing and injuring 

 of the ganghons that produees the effect, at least in the case 

 of the spider. 



Is the poison of tlie wasp a potion for prolonging life 

 in tlie stores, ratlier than an agent for producing paralysis? 

 Do wasps that attach their eggs to the cell walls, leave the 

 doors open until the young wasps hatch, for any particular 

 reason? These are questions that the experiment suggests. 

 But let us go back to the insect's life history. 



At birth the young wasp measures two and one-half 

 millimeters. It is a milky white grub of thirteen segments 

 counting the head, which is a round bead-like affair. As it 

 feeds and increases in size the distinction of the head de- 

 creases. At first the head is nearly the same diameter as 

 the body itself, but the latter soon takes on flesh and grows 

 many times its original size, so much more rapidly than the 

 head that it soon greatly surpasses it. 



I continued to feed my orphan for five days, which is 

 the average length of time spent gorging by the Guiana 

 grub. During this time it consumed several small spiders 

 that I paralyzed and placed before it, reaching in the end 

 a length of seven millimeters and turning a pale yellow color 

 much like clouded or partly sugared honey. 



Now the grub lies motionless for three days, when a 

 pellet of undigested bits of spider is deposited in the cell. 

 Xo cocoon of any kind is spun; instead it lies upon the bare, 

 hooped floor of the nursery, apparently quite contented. All 

 wasps rid themselves of what waste has accumulated during 

 larval life in this manner, a short time prior to pu])ation, the 

 majority placing it in the lower pole of the cocoon, where it 

 acts as a solid ])hio'. When the waste matter is expelled the 

 grub often loses its original color which is due only to the 



