EVOLUTION OF HIVE-BEE 285 



burrowers in sandy gardens, Halictus and Andrena, 

 form associations, either by several bees using one 

 gallery for entering and leaving their private nests ; 

 or by tunnelling close together and issuing in anger 

 at the disturbance of an intruder whose presence a 

 solitary bee would overlook ; or, again, by hibernating 

 in a little buried cluster, perhaps for the sake of 

 warmth. But whatever advantage is thus gained 

 is but small. The female bee is maid-of-all-work ; 

 she is still queen and worker ; she lives only for 

 a few weeks of spring, and dies before her young are 

 fledged. Her architectural instinct is as yet rudi- 

 mentary. The rude cells in which she lays her young 

 are lined with leaves or thistle-down, or stored in an 

 empty snail-shell, over which she piles a vast mass of 

 debris. 



The first indications of comb-construction are 

 found in the nest of the four-banded Halictus. This 

 little bee sinks a shaft into the earth, and at one side 

 enlarges the burrow so as to form a vault. In this 

 vault it constructs a row of from twelve to twenty- 

 four clay cells, arranged in tiers and only loosely 

 attached to the walls of the vault. The advantage 

 of this arrangement is that air can circulate more freely 

 around the cells, and drainage moisture from the 

 ground does not flow so directly on to them, a protec- 

 tion from mould that is enhanced by a prolongation of 

 the shaft below the level of the vault. In spite of 

 this improvement however, ' rot ' kills many of the 

 larva;. 



