The Mason-bees 



greatly In dimensions according to the num- 

 ber of workers and therefore to the age of the 

 nest first founded. Some of these nests are 

 hardly larger than one's hand, while others 

 occupy the greater part of the projecting edge 

 of a roof and are measured by square yards. 

 When working alone, which is not unusual, 

 on the shutter of a disused window, on a stone, 

 or on a twig in some hedge, the Sicilian Chali- 

 codoma behaves in just the same way. For 

 instance, should she settle on a twig, the Bee 

 begins by solidly cementing the base of her 

 cell to the slight foundation. Next, the 

 building rises, taking the form of a little up- 

 right turret. This first cell, when victualled 

 and sealed, is followed by another, having as 

 Its support, in addition to the twig, the cells 

 already built. From six to ten chambers are 

 thus grouped side by side. Lastly, one coat 

 of mortar covers everything, including the 

 twig itself, which provides a firm mainstay 

 for the whole. 



39 



