800 HYMENOPTERA 



of stone and puts them down the hole, and then proceeds 

 to ram it all down in a most workmanlike manner. 



Firmly gripping the lips of the hole with her middle 

 and hind legs, she launches herself with great force against 

 the loose earth, using the front of her broad head as a 

 battering ram, and making the loud buzz wherewith a 

 great effort is signalized. At length the burrow is filled 

 up flush with the surface, and it only remains to con- 

 ceal the fact that the spot is in any way different from 

 the surrounding terrain. Small stones are scattered over 

 the surface, a little loose dust is scratched about, and 

 the energetic Ammophila flies off to refresh herself on 

 a neighbouring flower head before commencing to excavate 

 a fresh burrow elsewhere. Unlike the Bembex, she will 

 never visit her burrow again ; it has been adequately 

 stocked with food once and for all. 



The above is a general description of the methods 

 adopted by the majority of Sphegidae, and we will turn 

 now to another great family of fossors, the Pompilidae, 

 which is broadly characterized by rather longer limbs, 

 and by the fact that they hunt spiders only. In essentials 

 they work in the same manner as the Sphegidae, but so 

 far as I can remember they work quietly, and never 

 make the excited buzzing so characteristic of Sceliphron 

 spirifex and other Sphegidae. 



But when it comes to the filling up of the stocked 

 burrow there is an important difference in the manner 

 of working, which I do not think has been sufficiently 

 appreciated. 



As described above, a Sphegid uses the front of her 

 broad head as a battering ram wherewith to press down 

 the loose earth ; but Pompilidae invariably use the end 

 of the abdomen. 



Sometimes the insect stands in the mouth of the hole 

 and quietly presses down the soil in the burrow, but one 

 specimen that I saw threw her body into such quickly 



