THE ANIMAL KINGDOM. 205 



about their task in the open air, on elevated monuments, 

 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 are in the shape of ovoid cells, each capable 

 of containing 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 in 

 the upper part, which it walls up hermetically before tak- 

 ing wing. 



The progeny of the bee thus finds itself inclosed alive in 

 a tomb, but maternal tenderness here displays all the re- 

 sources 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 par- 

 tition of masonry, it knows that it is provided with suffi- 

 cient air and nourishment to support 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 imprisoned. 1 



1 A species seen in England (jOsmia hicornis) selects as the material for its 

 nest banks of brown clay, 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. Tr. 



