136 THE INDUSTRIES OF ANIMALS. 



nursery ; on all these visits, in fact, the Bemhex fills 

 it up on leaving, and causes the disappearance of 

 all revealing traces. It is obliged to take so much 

 trouble, because it has not inherited from its ancestors 

 the receipt for the paralysing sting ; it throws itself 

 without care on its victim, delivers a few chance 

 blows, and kills it. Necessarily it cannot, under 

 these conditions, lay up provisions for the future ; 

 they would corrupt, and the larvse would not be 

 benefited; hence the obligation of frequently return- 

 ing to the nest, and of a perpetual hunt to feed 

 descendants whom nature has gifted with an excellent 

 appetite. According to the age of the offspring, the 

 mother chooses prey of different sizes ; at first she 

 brings small Diptera ; then, when it has grown, she 

 captures for it large blow-flies, and lastly gadflies.^ It 

 will be seen, then, that if we suppose the instinct of the 

 Sphex to be slowly developed by being derived from 

 a sting given at random, we make a supposition 

 which is quite admissible and rests on ascertained 

 facts. However this may be, the Bemhex, returning 

 to its burrow, is able to find it again with marvellous 

 certainty, in spite of the care taken to hide it by 

 removing every trace that might reveal its existence. 

 It is guided by an extraordinary topographic instinct, 

 which men not only do not possess, but cannot even 

 understand the nature of 



It would appear that certain Hymenoptera, fearing 

 to kill their victim with the sting, and not knowing 



' A Wasp found in La Plata, the Monedula fniiclala, as described 

 by Hudson [Naluralist in La Plala, pp. 162-164), is an adroit fly- 

 catcher, and thus supplies her grub with fresh food, carefully covering 

 the mouth of the hole with loose earth after each visit ; as many as six 

 or seven freshly-killed insects may be found for the use of one grub. 



