The Mason-Wasps 



for instance, are as good as Spiders and that 

 her family would accept them gladly. In- 

 stinct binds her down to the national diet. 



But, should the Epeira, the favourite 

 prey, be lacking, must the Pelopaeus give up 

 foraging? She will stock her warehouses 

 all the same, because any Spider suits her. 

 There you have discernment, whose elas- 

 ticity makes up, in certain circumstances, for 

 the excessive rigidity of instinct. Amid the 

 innumerable variety of game, the huntress is 

 able to discern between what is Spider and 

 what is not; and in this way she is always 

 prepared to supply her family, without quit- 

 ting the domain of her instinct. 



The Hairy Ammophila gives her larva a 

 single caterpillar, a large one, paralysed by 

 as many pricks of her sting as it has nerv- 

 ous centres in its thorax and abdomen. 

 Her surgical skill in subduing the monster 

 is instinct, displayed in a form that quashes 

 any inclination to see in it an acquired habit. 

 In an art that can leave no one to practise 

 it in the future unless that one be perfect at 

 the outset, of what avail are lucky chances, 

 atavistic tendencies, or the mellowing hand 

 of time? But the grey caterpillar, sacrificed 

 one day, may be succeeded on another day 

 by a green, yellow or striped caterpillar. 

 160 



