50 WASP STUDIES AFIELD 



to help start her nest. After this she dug rapidly, coming 

 out and visiting her spider six times while it lay in this 

 position. We do not know if she examined the spider fre- 

 quently in order to see if it was behaving properly, or to 

 gain an accurate idea of the required size of her hole. Next 

 she lugged it one foot nearer to the opening, dug out more 

 earth and again moved the spider nearer, to a spot only 

 nine inches from the hole. She always grasped the spider 

 by the middle of its ventral surface and carried it vertically, 

 the spider's hind legs dragging behind while the front ones 

 hung limp (fig. 9) ; she did not at any time drag it sidewise 

 by the legs as other Pompilids do. Furthermore, she always 

 walked backward when she had the burden and could not 

 see her way very well, so she constantly struggled over 

 obstacles that she might as easily have avoided if she could 

 have seen where she was going. 2 At one time in moving 

 her spider she struggled through grass and over a tangle 

 of weeds for fifteen inches, when a perfectly smooth clear 

 path lay beside her, all the way, less than two inches from 

 her at all points. 



She seemed now to feel the enthusiasm of seeing her 

 work nearing completion, and dug furiously for a few 

 minutes more; then she brought the spider very near and 

 hung it carefully on the tiny weed nearest to the hole, only 

 four inches distant, removed a few more mouth fuls and 

 kicked back the dirt, then dragged the arachnid to the mouth 

 of the burrow and attempted to take it in; but it was too 

 large, so she left it at the opening of the burrow and pro- 

 ceeded to deepen the hole, vigorously kicking the dirt out 

 all over the spider. She dug on and on in this way for an 



2 Another P. tropicus, in a different locality and year, moved her 

 spider in precisely the same manner, holding it vertically by the middle 

 of its ventral surface. She always walked backwards, galloping lightly 

 up absolutely perpendicular places, and even backing up overhanging 

 spots without evident difficulty, 



