The Hunting Wasps 



winged Sphex none but Crickets? Or, ac- 

 cording to time, place and circumstances, does 

 each make up for the lack of her favourite 

 victuals by others more or less equivalent? 

 To ascertain such facts, if they exist, would be 

 of the greatest importance, for they would tell 

 us if the inspirations of instinct are absolute 

 and unchangeable, or if they vary and within 

 what limits. It is true that the cells of one 

 and the same Cerceris contain the most varied 

 species of either the Buprestis or the Weevil 

 group, which shows that the huntress has a 

 great latitude of choice; but this extension of 

 the hunting-fields cannot be presumed in the 

 case of the Sphex-wasps, whom I have seen so 

 faithful to an exclusive victim, always the 

 same for each of them, and who moreover 

 find, among the Orthoptera, groups that differ 

 very widely in shape. Nevertheless, I have 

 had the good fortune to come upon one case, 

 one only, of complete change In the larva's 

 nourishment; and I record it the more will- 

 ingly in the Sphegian archives inasmuch as 

 such facts, scrupulously observed, will one 

 day form foundation-stones for any one who 

 cares to build up the psychology of instinct 

 on a solid basis. 



Here are the facts. The scene Is enacted 



122 



