The Mason-bees 



ber of eggs called for them; the Bee could 

 build there very comfortably, without hunt- 

 ing for another site, without leaving the peb- 

 ble to which she is attached by habit and 

 long acquaintance. It seems to me, therefore, 

 exceedingly probable that the family is a 

 small one and that it is all installed on the one 

 boulder, at any rate when the Mason-bee is 

 building a new home. 



The six to ten cells composing the cluster 

 are certainly a solid dwelling, with their rus- 

 tic gravel covering; but the thickness of their 

 walls and lids, two millimetres^ at most, seems 

 hardly sufficient to protect the grubs against 

 the inclemencies of the weather. Set on Its 

 stone in the open air, without any sort of 

 shelter, the nest will have to undergo the heat 

 of summer, which will turn each cell into a 

 stifling furnace, followed by the autumn 

 rains, which will slowly wear away the stone- 

 work, and by the winter frosts, which will 

 crumble what the rains have respected. How- 

 ever hard the cement may be, can it possibly 

 resist all these agents of destruction? And, 

 even if it does resist, will not the grubs, shel- 



^.078 inch. — Translator's Note. 

 22 



