144 INSECT LIFE x 



stone. There was no time for difficult mining, since 

 the prey must be stored as soon as possible ; she 

 needed light soil where the cell could be quickly- 

 made. I have already described her favourite soil — 

 dust deposed by years at the bottom of some hole 

 in a wall, or in some little hollow of a rock. The 

 Sphex which I was observing stopped at the foot of 

 a country house with a newly whitewashed fagade, 

 and measuring from six to eight metres in height. 

 Instinct told her that under the roof tiles she would 

 find hollows rich in ancient dust. Leaving her prey 

 at the foot of the fagade, she flew on to the roof. 

 For some time I saw her seek vainly about. Then, 

 having found a suitable position, she set to work 

 under the hollow of a tile. In ten minutes or a 

 quarter of an hour at most the domicile was ready ; 

 she flew down, promptly found the ephippiger, and 

 then had to carry up her prey. Would it be on the 

 wing, as circumstances suggest ? Not at all ; the 

 Sphex adopted the difficult method of escalading a 

 vertical wall with a surface smoothed by the mason's 

 trowel and from six to eight metres high. Seeing her 

 take this road, dragging her game between her feet, 

 I thought at first that it was impossible, but was 

 soon reassured as to the outcome of this audacious 

 attempt. Supporting herself by the little roughnesses 

 of the mortar, the vigorous insect, in spite of the 

 embarrassment of her heavy load, made her way up 

 this vertical plane with the same security, the same 

 speed, as on horizontal ground. The top is reached 

 without any hindrance, and the prey provisionally 

 deposited at the edge of the roof on the rounded 

 bark of a tile. While the Sphex was retouching her 



