ANIMAL BEHAVIOR, WITH EXAMPLES 199 



antagonists. They often show a disposition to prey on other 

 insects; their jaws are very powerful and they are always 

 ready to defend themselves. But even though provided with 

 such powerful weapons these grasshoppers are evidently not 

 equal to the attacks made by the possessor of the deadly 

 hypodermic instrument used by Sphex. 



Fabre ^ tells us of a species of Sphex observed by him in 

 Europe that stores her burrow with crickets. When she captures 

 her prey the insect is thrown on its back and the last segment 

 of the abdomen is firmly seized and fastened down with her 

 mandibles, while her feet clasp the sides, holding down the 

 body of the cricket. The wasp's front feet hold down the long 

 hind legs of her prey while her hind feet hold back the man- 

 dibles to prevent these from biting and at the same time 

 making tense the membraneous junction of the head and body. 

 In this attitude the Sphex darts her sting successively into 

 three nerve centres: first, into the one below the neck which she 

 has stretched back for the purpose; next, into the space behind 

 the prothorax, and lastly, into the one lower down. The cricket 

 thus paralyzed will live for six weeks or more. 



The wasp is so much smaller than its grasshopper prey, and 

 there is such a difference in actual weight between them, that 

 the wasp's bravery is all the more noteworthy. 



I have taken the opportunity of weighing both the wasp 

 and grasshoppers when fresh, with the following result: weight 

 of wasp, five grains; male meadow grasshopper, seven grains; 

 three female meadow grasshoppers, ten, eleven, and ten grains 

 respectively. It will be seen by these figures, first, that the 

 Sphex is able to carry a weight ecjual to twice that of her own 

 bodily weight; second, that the material supplied for her grow- 

 ing grub, after hatching from the egg, amounts in all to thirty- 

 eight grains, or more than seven times the weight of the female 

 parent. How much of this food supply is actually available 

 to the grub is not precisely known. The subtraction of the 

 weight of the chitinous material which is not edible would give 

 us only a rough estimate, as only the soft parts are eaten. 



In August of the following year, I studied the behavior of 

 several more of these wasps, one of which had stored three 

 1 " Souvenirs Entomologiques," 1879 and 1883. 



