30 THE SOLITARY WASPS. 



gradually acquiring the color and almost tk© thickness of the 

 caterpillar it had destroyed. 



Westwood states that Ammophila, when she has captured her 

 prey, walks backward, dragging it after her,* but in all the cases 

 that came under our notice she walked forward, the caterpillar 

 being grasped near the anterior end, in her mandibles, and either 

 lifted above the ground or allowed to drag a little if long and 

 heavy. It is usually held venter up, but in one case, in which 

 the wasp, while carrying it to her nest, frequently laid it down 

 and picked it up again, it was held with the venter down or up 

 indifferently. 



The all-important lesson that Fabre draws from his study of 

 the Ammophiles, is that they are inspired by automatically per- 

 fect instincts which can never have varied to any appreciable ex- 

 tent from the beginning of time. He argues that deviation from 

 the regular rule would mean extinction. For example, if the 

 wasp should sting ever so little to one side of the median line the 

 prey would be imperfectly paralyzed and the egg would conse- 

 quently be destroyed; or a sting in the wrong place might cause 

 the death of the caterpillar and thus the death of the wasp larva, 

 wdiicli, he thinks, can only be nourished by perfectly fresh food. 



The conclusions that we draw from the study of this genus 

 differ in the most striking manner from those of Fabre. The 

 one preeminent, unmistakable and ever present fact is variabil- 

 ity. Variability in every particular, — in the shape of the nest 

 and the manner of digging it, in the condition of the nest 

 (whether closed or open) when left temporarily, in the method 

 of stinging the prey, in the degree of malaxation, in the man- 

 ner of carrying the victim, in the way of closing the nest, and 

 last, and most important of all, in the condition produced in the 

 victims of the stinging, some of them dying and becoming "ver- 

 itable cadavei-s," to use an expressive term of Fabre's, long be- 

 fore the larva is ready to begin on them, while others live long- 

 past the time at which they would have been attacked and de- 

 stroyed if we had not interfered with the natural course of 



♦Introduction to Modem Classification of Insects, ^ol. II., p. 189. 



