654 Reflexes, Instincts, and Intelligence 



surroundings. The same thing may be seen when a number of social wasps 

 work together to replace the roof of their nest when it has been torn off. 



"An instance of the second class is seen in one of our examples of Pom- 

 pilus marginatus. This species, while searching for a nesting-place, leaves 

 its spider lying on the ground or hides it under a lump of earth, in either of 

 which positions the booty is subject to the attacks of ants; the wasp in ques- 

 tion improved upon the custom of her tribe by carrying the spider up into a 

 plant and hanging it there. We have now and then seen a queen of Polistes 

 fusca occupy a comb of the previous year instead of building a new one for 

 herself, showing a better mental equipment than her sisters who were not 

 strong-minded enough to change their ways and so built new nests along- 

 side of unoccupied old ones which were in good condition. In Bembex 

 society it is good form to close the door on leaving home, but sometimes a 

 wasp will save time by leaving the entrance open. This, however, is a 

 doubtful case, as the advantage would, perhaps, be more than balanced by 

 the exposure of the nest to parasites. The most conspicuous example that 

 we have seen of intelligence among wasps was in that individual of Ammo- 

 phila that rose above her fellows by using a stone to pound down the earth 

 over her nest. 



" The general impression that remains with us as a result of our study of 

 these activities is that their complexity and perfection have been greatly over- 

 estimated. We have found them in all stages of development and are con- 

 vinced that they have passed through many degrees, from the simple to the 

 'complex, by the action of natural selection. Indeed, we find in them beau- 

 tiful examples of the survival of the fittest." 



In a short note published after the issuance of their book, the Peckhams 

 describe an experiment with a Sphex whose results to their minds plainly 

 show the tempering of the Sphex instinct by a certain degree of intelligence. 

 Fabre once experimented on a Sphex, taking advantage of the moment that 

 the wasp was out of sight below to remove her prey to a little distance with 

 the result that when the wasp came up she brought her cricket to the same 

 spot and left it as before, while she visited the interior of the nest. Since he 

 repeated this experiment about forty times, and always with the same result, 

 it seemed fair, says the Peckhams, to draw the conclusion that nothing less 

 than the performance of a certain series of acts in a certain order would 

 satisfy her impulse. She must place her prey just so close to the doorway; 

 she must then descend and examine the nest, and after that must at once 

 drag it down, any disturbance of this routine causing her to refuse to pro- 

 ceed. 



"We recently found a Sphex ichneumonea at work storing her nest," 

 continue the Peckhams, "and thought it would be interesting to pursue 

 Fabre's method and find out whether she were equally persistent in follow- 



