280 A BOOK OF INSECTS 



burrows, where they remain until the following spring, 

 when they commence preparations for the new brood. 

 Most other solitary bees remain in their cells as larva? or 

 pupa? throughout the winter, the sexes issuing together 

 during spring or early summer. 



Humble-bees exemplify the true social community in 

 its simplest form. The mother bee, or " queen," becomes 

 the foundress of a co-operative colony, which ultimately 

 includes a preponderance of workers — i.e. small, imper- 

 fectly developed females, which act as nurses, foragers, 

 and builders. Some humble-bees build their nests in 

 holes, others upon the surface of the ground beneath a 

 pile of moss or vegetable debris. The queen of a sub- 

 terranean species, such as our black-and-yellow banded 

 humble-bee with a tawny tail (Bombus tcrrestris), often 

 takes possession of a ready-made cavity, such as the 

 deserted burrow of a field mouse. Here she constructs a 

 rough cell, using a waxy substance, and coats the inner 

 walls liberally with honey-saturated pollen. Four or five 

 eggs are then laid, and the cell is closed ; but it is re- 

 opened from time to time as the growing grubs require 

 more food. The queen's next care is to make one or two 

 cells which she fills with pollen and honey, these reser- 

 voirs being drawn upon in rainy weather when food cannot 

 be gathered direct from the flowers. Thereafter she pro- 

 ceeds to fashion more brood cells, and to lay more eggs, 

 labouring the while to provide food for the grubs which 

 have already hatched. As the latter increase in size 

 they press against the soft walls around them, while the 

 queen continually adds fresh layers from without; so 

 that the cell gradually becomes an irregular truffle-like 

 mass. When full-grown, each grub spins an ovoid silken 

 cocoon. 



In favourable circumstances the development of the 



