384 



EVOLUTION AND ANIMAL LIFE 



divides this space into a few cells by means of 

 transverse partitions (Fig. 236). In each cell 

 she lays an egg, and puts with it enough food 

 — flower pollen — to last the grub or larva 

 through its hfe. She then waits in an upper 

 cell of the nest until the young bees issue 

 from their cells, when she leads them off, and 

 each begins active life on its own account. 

 The mining bees Andrena, which make little 

 burrows (Fig. 237) in a clay bank, live in large 

 colonies — that is, they make their nest bur- 

 rows close together in the same clay bank, but 

 each female makes her own burrow, lays her 

 own eggs in it, furnishes it with food — a kind 

 of paste of nectar and pollen — and takes no 

 further care of her young. Nor has she at any 

 time any special in- 



Fig. 236.— Nest 

 of carpenter 

 bee, Ceratina 

 dupla. 



terest in her neigh- 

 bors. But with the 

 smaller mining bees, 

 belonging to the 

 genus Halictus, several 

 females unite in mak- 

 ing a common burrow, after which 

 each female makes side passages of 

 her own, extending from the main or 

 public entrance burrow. As a well- 

 known entomologist has ssiid, Andrena 

 builds villages composed of individual 

 homes, while Halictus makes cities 

 composed of apartment houses. The 

 bumblebee (Fig. 238), however, es- 

 tablishes a real community with a 

 truly communal life, although a very 

 simple one. The few bumblebees 

 which we see in winter time are 

 queens; all other bumblebees die in 

 the autumn. In the spring a queen 

 selects some deserted nest of a field 

 mouse, or a hole in .the ground, 

 gathers pollen which she molds into 



Fig, 237. — Nest of the Andrena, 

 the mining bee. 



