THE SAND-LOVING AMMOPHILA 213 



Unfortunately, we had to go then, so we dug up the nest. 

 We watched carefully for the tiny Diptera larvae, but if 

 they were there they were lost in the digging. 



Two minutes is all the time the wasp requires for adjust- 

 ing her prey and ovipositing, and sometimes she is through 

 in less time. ( Figure 47 shows the position of the egg on the 

 caterpillar.) Then begins the task of filling the hole, and in 

 this she works in a most calm and purposeful manner, dis- 

 turbed of course if one crowds too near, but with no silly 



FIG. 47. Position of egg on caterpillar. Natural size. 



nervousness. She emerges head first and immediately gets 

 some small clods, usually about three, and takes them down 

 to the bottom. We suspect that she arranges these to serve as 

 a partition between the chamber and the burrow, to prevent 

 the loose soil from being packed down around the cater- 

 pillar or crowded upon the delicate egg. Then she jumps 

 out nimbly and scratches and kicks the loose dirt nearby 

 into the hole, goes in and stands on her head, pounding and 

 packing it down. With each ram of the head, she emits 

 a shrill buzzing sound. How this buzz is made we do not 

 know, nor do we know whether it is an expression of pleas- 

 ure, or of lalpor, or a mechanical part of the effort. Thus she 

 brushes in and packs down several layers of loose dirt, until 

 the hole is filled almost to the top. If she uses all the 

 loose dirt lying nearby, she is not in the least disconcerted, 

 but simply bites some more loose, with her mandibles, from 

 the surface of the ground and uses that. When the de- 

 pression is yet about one- fourth inch deep, she fetches a 

 large, firm clod, sometimes as much as five times as large 

 as her own head, and throws it into the hole. At first it 



