HYMENOPTEEA. 



363 



occupy themselves in building new cells, and in raising the wall 

 of enclosure which is to protect the nest. This wall, formed of 

 wax, starts from the base and raises itself, like a vertical rampart, 

 from every point in the circumference. They then surmount 

 this by the first roof, which is flat, . supported by some pillars, 

 and in which they have left one or two irregular openings. The 

 whole is finally protected by a hemispherical covering of moss, 

 made into a sort of felt and lined with wax. Fig. 335 represents, 

 in its entirety, a nest of this humble bee. 



Fig. 335. Nest of the Moss Humble Bee (Bombusmuscorum). 







The workers also take their part in rearing the eggs. They 

 bring the paste, which they slip into the cells to the larvae by 

 a small hole, which is shut immediately afterwards. Later, they 

 again give their assistance in disengaging the pupae from their 

 envelopes. In short, they make themselves generally useful ; 



