18 BEES AND WASPS [OH. 



Pompilus rufipes is rather smaller than P. viaticus, 

 and is black with a few white spots on each side of 

 the abdomen. The female is a very fussy individual 

 and shy of being observed : like all her relations she 

 provisions her nest with spiders. Different individuals 

 adopt varying methods for the concealment of their 

 completed burrow : one, whom I had watched stock- 

 ing her nest, had driven the burrow horizontally just 

 below the surface of the sand for a distance of about 

 two and a half inches before striking obliquely down- 

 ward. When all was ready for closure she worked 

 for a long while to and fro on the side walls of her 

 horizontal tunnel until eventually she so weakened 

 them that the whole length of the roof collapsed 

 simultaneously, leaving a shallow trough along the 

 surface of the ground. The wasp seemed quite pre- 

 pared for this effect, for so soon as she had shaken 

 herself clear of the sand which fell on to her, she set 

 to work to level up the trough by scratching sand 

 into it from all directions in turn: there was thus 

 formed a scratched patch of about three inches dia- 

 meter around the site of her tunnel : the scratching 

 had exposed the tips of a few buried pine-needles ; 

 these the wasp pulled up and laid flat on the ground, 

 and then dragged a few rabbit's pellets on to the 

 patch, and then at length was satisfied. A second 

 individual on another occasion having sunk a nearly 

 vertical shaft, filled it when stocked by scratching 



