Chapter iv 



THE YELLOW-WINGED SPHEX 



Under their powerful armour, which no dart 

 can penetrate, the insects of the Beetle tribe 

 offer but a single vulnerable spot to the sting- 

 bearing enemy. This defect in the breastplate 

 is known to the murderess, who drives in her 

 poisoned dagger there and at one blow strikes 

 the three motor centres, for she selects her 

 victims from the Weevil and Buprestis families, 

 whose nervous system is centralized to the 

 requisite degree. But what will happen when 

 the prey is an insect clad not in mail but in a 

 soft skin, which the Wasp can stab here or 

 there indifferently, in any part of the body that 

 chances to be exposed ? In that case are the 

 blows still delivered scientifically ? Like the 

 assassin who strikes at the heart to cut short 

 the dangerous resistance of his victim, does the 

 assailant follow the tactics of the Cerceres and 

 wound the motor ganglia by preference ? If 

 that be so, then what happens when these 

 ganglia are some distance apart and so inde- 



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