DWELLINGS. 



169 



diameter of which is about equal to the size of the 

 insect's body. The Xylocopa thus forms a tube about 

 thirty centimetres in length. Quite at the bottom 

 she places the first egg, leaving beside it a provision 

 of honey necessary to nourish the larva during its 

 evolution ; she then closes it with a partition. This 

 partition is made with fragments of the powder of 

 wood glued together with saliva. A first horizontal 



Fig. 22. 



ring is applied round the circumference of the tube ; 

 then in the interior of this first ring a second is 

 formed, and so on continuously, until the central 

 opening, more and more reduced, is at last entirely 

 closed up. This ceiling forms the floor for the next 

 chamber, in which the female deposits a new egg, 

 provided, like the other, with abundant provisions. 

 The same acts are repeated until the retreat becomes 



