The Mason-bees 



fixed on a pomegranate-branch. It comprised 

 eight cells, of which seven were occupied by 

 the Chalicodoma and the eighth by a little 

 Chalcis, the plague of a whole host of the 

 Bee-tribe. Apart from this instance, which 

 was not a very serious case, I have seen 

 nothing. In those aerial nests, swinging at the 

 end of a twig, not a Dioxys, a Stelis, an 

 Anthrax, a Leucospis, those dread ravagers 

 of the other two Masons; never any Osmiae, 

 Megachiles or Anthidia, those lodgers in the 

 old buildings. 



The absence of the latter is easily ex- 

 plained. The Chalicodoma's masonry does 

 not last long on its frail support. The win- 

 ter winds, when the shelter of the foliage 

 has disappeared, must easily break the twig, 

 which is little thicker than a straw and liable 

 to give way by reason of its heavy burden. 

 Threatened with an early fall, if it is not al- 

 ready on the ground, last year's dwelling is 

 not restored to serve the needs of the present 

 generation. The same nest does not serve 

 twice; and this does away with the Osmiae 

 and with their rivals in the art of utilizing 

 old cells. 



The elucidation of this point does not re- 

 274 



