FOREST SHELL-WASP 411 



slender needle I stab the cephalothorax in two places, once 

 from above, once from below. My object is to reach the 

 ganglions mentioned above, thereby injuring them with my 

 needle and producing a sort of paralysis in the spider. The 

 experiment works well enough. The victim quivers for a 

 moment, then lies motionless. With my crude sting, repre- 

 sented by the needle, I have imitated as closely as possible 

 the methods employed by the parent wasp in preparing food 

 for her offspring. 



Now I place the spider in the cell just under the sus- 

 pended unhatched egg of the wasp and await developments. 

 In two days the young wasp emerges from the shell, and 

 hangs head down, still attached at its anal segment to the 

 cell wall. For several hours I keep close watch, during 

 which time it pays no attention to the paralyzed spider. It 

 scorns my work and the repast I have prepared and hangs 

 helplessly, its mouth sucking rythmically at the air. Now 

 I move the spider so that one of the stab wounds in its body 

 comes in contact with the larva's mouth. It responds fran- 

 tically, like a creature dying of thirst, to the liquid that oozes 

 from the wound. It fastens itself by the mouth to its victim 

 and there it clings like a suction pad, its entire body rippling 

 as it drains the spider's life. 



Much to my surprise the experiment is crowned with 

 success. In a few hours a change is noticeable in the larva 

 it has grown and gained in strength. At length it pulls 

 away from the walls of the cell and settles among the spiders 

 I have provided. It is an experiment especially prolific in 

 answering abstract questions and suggesting others. It 

 proves that all larva are not entirely dependent on one cer- 

 tain article of diet. Doubtless a given species is invariably 

 supplied by the parent with the same kind of food, yet we 

 have positive proof that such a condition is not imperative. 

 The larva has no more abhorrence for the spider than for its 

 natural diet of caterpillars. If the mother wasp but knew 



