266 AN INTRODUCTION TO ZOOLOGY 



(4) SOLITARY BEES WITH A TENDENCY TOWARD COMMUNITY 

 LIFE. The mining bees of the genus Halictus make burrows in 

 sand banks and the sides of cliffs (Fig. 149, A). "A remarkable 

 feature in the habits of the bees of this genus is that several 

 females unite in making a burrow into a bank, after which each 

 female makes passages extending sidewise from this main burrow 

 or public corridor to her own cells. While Andrena builds vil- 

 lages composed of individual homes, Halictus makes cities com- 

 posed of apartment houses " (199, p. 666). 



(5) SOCIAL BEES WITH ANNUAL COLONIES. The bumblebees 

 of the genus Bombus form communities composed of queens, males, 

 and workers. Only young fertilized queens survive the winter. 

 In the spring each selects an old deserted field-mouse nest and 

 starts a colony. First a number of workers are reared, being 

 cared for by their mother; these workers then take over the 

 household duties, and the queen devotes herself to laying eggs. 

 As autumn approaches males and queens appear, and finally all 

 perish except the young queens. 



(6) SOCIAL BEES WITH PERMANENT COLONIAL LIFE. The 

 honeybee differs from the bumblebee in many ways. Its life ac- 

 tivities are more complex, and its colonies are able to pass the 

 winter without perishing. That their complex community life 

 had evolved from a solitary condition through the stages men- 

 tioned above should not be understood, but the life histories of 

 the solitary bees and the bumblebee show many gradations be- 

 tween the strictly solitary life and the complex social lives of 

 these remarkable insects. 



