THE ANIMAL KINGDOM. 213 



set about their task in the open air, on our elevated monu- 

 ments, or near the tops of trees. 



The Wall Megachile {Xylocopa, Fabricius), commonly 

 called the mason-bee, has acquired great celebrity from its 

 nests built of small stones or of mortar which it attaches to 

 houses. They represent ovoid cells, each capable of con- 

 taining a hazel-nut. These are so many lodgings to which 

 this fly intrusts its progeny. When after long toil the 

 miniature monument is finished, the mother places one of 

 its eggs inside it, and then retreats by the opening left 

 patent on the upper part, which it walls up hermetically 

 before taking wing. 



The progeny of the bee thus finds itself inclosed alive 

 in a tomb, but maternal tenderness here displays all the 

 resources of the greatest foresight. Before leaving, the 

 Megachile lines the walls with a fine hanging of silk. 

 Thus the larva is sheltered from the night cold, and has 

 not to dread contact with the rough walls of its little 

 chamber. By dint of laborious journeys the mother has 

 contrived to amass in the cradle a sufficient quantity of 

 food for its little one. And when it incloses it in its cell 

 by means of a partition of masonry, it knows that it is pro- 

 vided with sufficient air and nourishment to supi^ort it, 

 and that when the moment comes for it to take flight, 

 it will, like its mother, be in possession of working- 

 implements to break down the wall within which it is 

 imj)risoned.' 



In those countries where the mason-l)ees are very rare, 

 their nests are isolated, or there are only a few alongside 



• A sjieciea seen in England (O-imia hicornis) selects as tlie matei-iul for its nest 

 banks of brown claj', which it moistens with saliva, and moulds into pellets 

 as large as peas. It is supposed that a bee will prepare as many as 140 to 

 180 of these pellets in a day. The Megachile sicida is not met with in this 

 country. — Te. 



