The Mason-bees 



Three-horned Osmla, the Mason-bee's visi- 

 tor. 



All solitary though she be on her boulder, 

 which would seem the proper thing to keep 

 away exploiters, the scourge of dense popu- 

 lations, the Chalicodoma of the Pebbles is no 

 less sorely tried. My notes abound in cases 

 such as the following: of the nine cells in one 

 dome, three are occupied by the Anthrax, two 

 by the Leucospis, two by the Stelis, one by the 

 Chalcidid and the ninth by the Mason. It is 

 as though the four miscreants had joined 

 forces for the massacre: the whole of the 

 Bee's family . has disappeared, all but one 

 young mother saved from the disaster by her 

 position in the centre of the citadel. I have 

 sometimes stuffed my pockets with nests re- 

 moved from their pebbles without finding a 

 single one that has not been violated by one 

 or other of the malefactors and oftener still 

 by several of them at a time. It is almost 

 an event for me to find a nest intact. After 

 these funereal records, I am haunted by a 

 gloomy thought: the weal of one means the 

 woe of another. 



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