XX MASON BEES 283 



has to be closed. This is all done without delay. 

 The orifice is closed by a cover of undiluted mortar, 

 worked from the circumference to the centre. Two 

 days at most seem required for the whole work, 

 unless bad weather or a cloudy day should interrupt 

 it. Then, backing on the first cell, a second is 

 built and stored in the same way, and a third and 

 fourth, etc., follow, each one with honey and an egg, 

 and closed before another is begun. Work once begun 

 is continued until it is completed, the bee never 

 building a new cell until the four acts required to 

 perfect the preceding one are performed — namely, 

 construction, provisioning, an egg, and sealing the 

 cell. 



As Chalicodoma muraria always works alone on 

 her chosen boulder, and shows great jealousy if 

 her neighbours alight there, the number of cells 

 clustered on one pebble is not great — usually six to 

 ten. Are some eight larvae her whole progeny, or 

 will she establish a more numerous family on other 

 boulders ? The surface of the stone would allow of 

 more cells if she had eggs for them, and the bee 

 might build there very comfortably without hunting 

 for another, or leaving the one to which she is 

 attached by habit and long acquaintance. I think, 

 therefore, that most probably all her scanty family 

 are settled on the same stone — at all events when 

 she builds a new abode. 



The six or ten cells composing the group are 

 certainly a solid dwelling, with their rustic covering 

 of gravel, but the thickness of their walls and lids — 

 two millimetres at most — hardly seems sufficient 

 against rough weather. Set on its stone in the open 



