WASPS, SOCIAL AND SOLITARY 



of her thorax. Each works after her own fashion, and 

 in a way that is uniform for each species. 



The capturing of the victim and caring for it before 

 the hole is made, as in the case of P. quinquenotatus, or 

 the reverse mejhod, pursued by Astata, Ammophila, 

 Bembex, and others, of preparing the nest before the 

 food supply is secured, is certainly instinctive ; as is 

 also the way in which some of these wasps act after 

 bringing the prey to the nest. For example, S. ichneu- 

 monea places her grasshopper just at the entrance to 

 the excavation, and then enters to see that all is right 

 ]3efore dragging it in. Under natural conditions this 

 order is never varied, although the wasp can adapt 

 herself to different circumstances when occasion de- 

 mands. Again, we see Oxybelus scratching open her 

 nest while on the wing, and entering at once with the 

 fly held tightly in her legs. Each way is characteristic 

 of the species, and would be an important part of any 

 definition of the animal based upon its habits. 



The general style of the nest depends upon instinct. 

 Trypoxylon uses hollow passages in trees, posts, straws, 

 or brick walls ; Diodontus americanus, a member of the 

 same family, always burrows in the ground, as do Bem- 

 bex, Ammophila, and Sphex. In the case of Trypoxylon 

 the passage may be ready for use or may require more 



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