Wasps, Bees, and Ants 503 



The social wasps all belong to the single family Vespidae, which includes 

 but three genera of American wasps, of which one is limited to the Pacific 

 coast. These three genera may be distinguished by the following characters: 



Social wasps with abdomen broad and truncate at base (next to thorax) . .VESPA. 



Social wasps with abdomen spindle-shaped, tapering at both ends POLISTES. 



Social wasps with abdomen pedunculate, i.e., basal segment elongated to form a stem 

 or peduncle ; occurring only on Pacific coast POLYBIA. 



All these wasps fold the wings longitudinally when at rest, and in all 

 there exist three castes or kinds of individuals in each species, namely, males, 

 females, and sterile workers. Like the worker bees, worker wasps are 

 winged, not wingless, as the worker ants are. 



The "social" habit, as distinguished from the "solitary" habit charac- 

 teristic of all the wasps we have so far studied, consists of the founding and 

 maintenance of communities by the living together in a single group through 

 the spring, summer, and autumn of all the offspring, males, females, and 

 workers, of a single fertilized female, the queen. This community is thus 

 a single family, often indeed very large, which busies itself about the 

 care of a family nest. The nest may be underground or suspended from 

 the branch of a tree, placed under the eaves of a building or otherwise 

 supported above ground. It is built of paper made by moistening bits 

 of old wood with saliva and chewing them into pulp, and consists of one or 

 more horizontally placed tiers or combs of cells, exposed or enclosed by 

 paper envelopes, in which a single entrance and exit opening is left. 



The castes or kinds of individuals are not so distinctly recognizable by 

 structural differences as with the social bees and the ants, but the sexual 

 forms, males and females, are always obviously larger than the workers 

 (Fig. 709). The special functions of the different castes are (i) the mating 

 with the females by the males; (2) the building of the queen-nest (the minia- 

 ture early spring nest, see next paragraph), the gathering of food for the 

 first, early spring generation, and the laying of eggs for all the broods by 

 the females; (3) the bringing of food, and the enlarging and building and 

 care of the nest and of the young by the workers. 



It has already been mentioned that a community holds together through 

 part of the year only. The life-history of a community is in general outline 

 as follows: In the early spring fertilized females (queens) which have hiber- 

 nated (as adults) in sheltered places, as crevices in stone walls, under logs, 

 stones, etc., come out from their winter hiding-places and each makes a small 

 nest (of the kind characteristic of its species, see later) containing a few 

 brood-cells. In each cell an egg is laid, and food, consisting of insects, killed 

 and somewhat masticated, is hunted for and brought to the larvae throughout 

 their brief life by the queen. The larvae soon pupate in the cells and in a 



