TIELD AND STUDY 



he knows full well that the insect does the deed 

 without thought or previous experience. 



The Sphex wasp seems to know that the cricket 

 upon which it preys has three nerve-centres that 

 control its main movements, and hence requires 

 three stings in three different parts of its body to 

 produce complete paralysis, while another species 

 of wasp, the Cerceris, knows her beetle has only one 

 nerve-centre, and hence she stings it but once. 



The wasp called the Ammophila sometimes 

 pinches and bruises the brain of the grub she has 

 stung and is carrying to her nest, in order to in- 

 crease its torpor, but Fabre says she knows just 

 where to stop; she "knows quite well that to inflict 

 a mortal wound on the cervical ganglia would mean 

 killing the caterpillar then and there, the very thing 

 to be avoided." Of course, the wasp knows nothing 

 about nerve-ganglia and their functions. This is the 

 untaught wisdom of her race, of which she is the 

 unwitting instrument. It is an ancestral knowledge 

 which Nature infused into her organism before she 

 was born. 



The Sphex wasp needs at times to paralyze the 

 mouth-parts of the game she is carrying to her den, 

 so that it cannot impede her progress by seizing 

 upon blades of grass by the way, and also that she 

 may lessen the danger of the beetle's seizing and 

 wounding her with its mandibles ; and, like a trained 

 surgeon, she knows the precise spot in the beetle's 

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