VI 



THE YELLOW-WINGED SPHEX 



In their impenetrable coat of mail the Cole- 

 optera offer but one vulnerable point to their dart- 

 bearing foe. This defect in the cuirass is known to 

 the assassin, and the poisoned sting is there inserted, 

 striking at one blow the three centres of motion, 

 the Weevil and Buprestid, which alone have a nervous 

 organisation sufficiently centralised, being selected. 

 But what happens when the insect wears no armour 

 and is soft-skinned, so that the Hymenopteron can 

 pierce it anywhere that the chances of the struggle 

 may direct ? Is there then a choice as to where the 

 blow is given ? Like the assassin who strikes at 

 the heart to shorten the dangerous struggles of his 

 victim, does the Sphex follow the tactics of the 

 Cerceris, and strike by preference at the motor 

 ganglia ? If so, what happens when these are 

 distant from one another, acting so independently 

 that paralysis of one does not affect the others ? 

 These questions will be answered by the history 

 of an insect which hunts field crickets, Sphex flavi- 

 pennis. 



It is towards the end of July that this Sphex 



80 



