xiv J THE ENEMIES OF SPIDERS 125 



be deprived of all power of motion, otherwise the egg 

 will stand a great chance of being displaced and 

 crushed, and even if it hatches it will be unable to 

 commence its meal upon the struggling spider. 



Now in the whole range of animal instinct there 

 is nothing more remarkable than the manner in which 

 the solitary wasps have learnt to solve this problem. 

 The solution lies in so stinging the victim that it is 

 paralysed but not killed, and though quite unable to 

 move, it neither shrivels nor decays, but remains 

 perfectly sound and edible for two or three weeks. 

 To accomplish this result the wasp acts as though 

 it possessed a knowledge of the minute anatomy of 

 its victim, and knew to a hair's breadth the position 

 of the principal nerve ganglia which control its 

 actions. Into these it unerringly thrusts its sting. 

 But even accuracy of aim is not everything ; there 

 must be the finest discrimination in the severity of 

 the wound. A slight excess, and the animal is killed ; 

 too timid a thrust will not destroy movement. When 

 the delicate operation has been successfully performed, 

 the paralysed spider is dragged into the cell, placed 

 on its back, and an egg carefully deposited at the 

 base of its abdomen, after which the cell is sealed up. 

 Some wasps, instead of providing a single large 

 spider, store their cells with a number of smaller 

 victims, all rendered limp and motionless. 



In attacking a spider the first action of one of 



