Wasps, Bees, and Ants 517 



few square yards of the many yards of exposed surface. The nest-tunnels 

 were capped by curious little chimneys, mostly curving so as to present the 

 opening not directly upward, exposed to rain, but to one side or almost down- 

 ward, thus preventing the flooding of the open burrows by water. Similar 

 villages or colonies are made by the little short-tongued mining-bees of the 

 genus Andrena. Comstock has noted Andrena villages covering only one 

 square rod of ground that included several thousand nests, and he received 

 from a correspondent "a description of a collection of nests of this kind 

 which was fifteen feet in diameter, and in the destruction of which about 

 2000 bees were killed a terrible slaughter of innocent creatures." 



A step farther in this social tendency is exhibited by the smallest of all 

 our mining-bees, the tiny little short-tongued bees of the genus Halictus, 

 the various species measuring from -jV to T 3 o of an inch in length. While each 

 female forms her own nest-cells, lays eggs in them, and provisions them, she 

 is one of a number of females that work together to build a common vertical 

 tunnel with single external opening, along the sides of which the various 

 cells are arranged. In this way one entrance and one corridor, built and 

 used by several individuals in common, serve to give access to several dis- 

 tinct homes, i.e., nest-cells. These groups of homes with common corridors 

 and openings are placed thickly together in populous sand-bank colonies. 

 Thus, as Comstock aptly puts it, "while Andrena builds villages composed 

 of individual houses, Halictus makes cities composed of apartment-houses." 



The next stage exhibited among present-day bees in this progressive 

 specializing of the gregarious tendency is the condition under which the 

 bumblebee lives. This is a long leap from the apartment-house life of Halic- 

 tus, and does not explain how the differentiation into castes, i.e., the estab- 

 lishment of the worker (rudimentary female) caste, composed in some 

 cases of two distinct sizes, worker majors and worker minors, has come 

 about. If we could but know the intermediate sociologic stages which were 

 exhibited by bees now extinct (or, if living, not yet discovered), but that cer- 

 tainly existed not very long ago (as geologic time-reckoning goes), the mar- 

 velous division of labor, differentiation of structure, and commensal inter- 

 dependence of individuals displayed by the honey-bees would be divested 

 of much of its mystery. 



The bumblebees possess a domestic economy wholly like that of 

 the social wasps (yellow-jackets and hornets). In each species there are 

 three kinds of individuals, males, fertile females, and workers (infertile 

 females) which are sometimes of two constant sizes, called worker majors 

 and worker minors. The workers are all distinctly smaller than the fertile 

 females and usually differ somewhat in marking (Fig. 723). The only indi- 

 viduals to over-winter are fertilized females, queens, which hibernate as 

 queen wasps do in sheltered places, as crevices in stone walls, holes in the 



