The Great Cerceris 19 



trodden, compact soil, such as that of a path, 

 to prevent the possibiUty of landsUps and other 

 damage which would ruin her gallery at the 

 first shower of rain. Ours, on the contrary, is 

 not very particular about the nature of her 

 soil, but must have that soil vertical. With 

 this slight architectural modification, she avoids 

 most of the dangers that might threaten her 

 gallery ; and consequently she digs her bur- 

 rows indifferently in a loose and slightly clayey 

 soil and in the soft sand of the Molasse forma- 

 tion, which makes the work of excavation 

 much easier. The only indispensable condition 

 appears to be that the earth should be dry 

 and exposed to the sun's rays for the best part 

 of the day. It is therefore in the steep road- 

 side banks, in the sides of the ravines hollowed 

 by the rains in the sandstone, that our Wasp 

 elects to establish her home. These conditions 

 are common in the neighbourhood of Carpen- 

 tras, in the part known as the Hollow Road ; 

 and it is here that I have observed Cerceris 

 tuberculata in her largest numbers and that I 

 gathered most of my facts relating to her 

 history. 



The choice of this vertical site is not enough 

 for her : other precautions are taken to guard 

 against the inevitable rains of the season, 

 which is already far advanced. If there be 



