THE FOREST SHELL-WASP 57 



tive proof that such a condition is not imperative. The larva has 

 no more abhorrence for the spider than for its natural diet of cater- 

 pillars. If the mother wasp but knew the truth she might store her 

 nest with the ever abundant spider in years of caterpillar scarcity. 



Further, the experiment points out that in the wasp's victim, 

 paralysis may be brought about by the thrust of the dart unaided by 

 its poison. It is the stabbing and injuring of the ganglions that pro- 

 duces the effect, at least in the case of the spider. 



Is the poison of the wasp a potion for prolonging life in the stores, 

 rather 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 \vhite 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 decreases. 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 un- 

 digested bits of spider is deposited in the cell. No 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 pupation, the majority placing it in the lower pole of the cocoon, 



