Advanced Theories 



a Sphex in the strict sense of the word. 

 Then what did he see? 



The term Fly, by which the captured prey 

 is designated, is a very elastic word, which 

 can be applied to the immense order of 

 Diptera and which therefore leaves us unde- 

 cided among thousands of species. The ex- 

 pression Sphex is most likely also employed 

 in an equally indefinite sense. At the end of 

 the eighteenth century, when Darwin's book 

 appeared, this expression was used to denote 

 not only the Sphegids proper, but particularly 

 the Crabronidae. Now, among the latter, 

 some, when storing provisions for their larvae, 

 hunt Diptera, Flies, the prey required by the 

 unknown Hymenopteron of the English 

 naturalist. Then was Darwin's Sphex a 

 Crabro? No; for these Dipteron-hunters, 

 like the hunters of any other prey, want game 

 that keeps fresh, motionless but half-alive, for 

 the fortnight or three weeks required for the 

 hatching of the eggs and the complete de- 

 velopment of the larvae. All these little 

 ogres need meat killed that day and not gone 

 bad or even a little high. This is a rule to 

 which I know of no exception. The word 

 Sphex cannot be accepted therefore, even with 

 its old meaning, 



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