216 THE WONDERS OF INSTINCT 



In the end, another idea occurred to me and made 

 me doubt whether my rebuffs were always due to clumsy 

 accidents. The Eumenes' cells are crammed with game : 

 there are ten caterpillars in the cell of Eumenes Amedei 

 and fifteen in that of Eumenes pomiformis. These 

 caterpillars, stabbed no doubt, but in a manner unknown 

 to me, are not entirely motionless. The mandibles 

 seize upon what is presented to them, the body buckles 

 and unbuckles, the hinder half lashes out briskly when 

 stirred with the point of a needle. At what spot is 

 the egg laid amid that swarming mass, where thirty 

 mandibles can make a hole in it, where a hundred and 

 twenty pairs of legs can tear it? When the victuals con- 

 sist of a single head of game, these perils do not exist; 

 and the egg is laid on the victim not at hazard, but upon 

 a judiciously chosen spot. Thus, for instance, Ammo- 

 phila hirsuta fixes hers, by one end, cross-wise, on the 

 Gray Worm, on the side of the first prolegged segment. 

 The eggs hang over the caterpillar's back, away from 

 the legs, whose proximity might be dangerous. The 

 worm, moreover, stung in the greater number of its 

 nerve-centers, lies on one side, motionless and incapable 

 of bodily contortions or sudden jerks of its hinder seg- 

 ments. If the mandibles try to snap, if the legs give a 

 kick or two, they find nothing in front of them: the 

 Ammophila's egg is at the opposite side. The tiny grub 

 is thus able, as soon as it hatches, to dig into the giant's 

 belly in full security. 



How different are the conditions in the Eumenes' cell. 

 The caterpillars are imperfectly paralyzed, perhaps be- 



