534 



NATURAL HISTORY OF ARTHROPODS. 



largest, and according to the species, from a few individuals to several thousands. 

 These communities, unlike those of the hive-bee or of ants, have only a temporary 

 existence. On the approach of winter the males and workers perish, and the fertile 

 females crawl into such protected situations as crevices in walls or under the bark of 

 trees, and there pass the winter in a dormant state. In the following spring each 

 surviving female founds a new colony. At first she performs the duties of both queen 

 and worker. A small nest is made, eggs are laid in it, and when the larvas hatch, they 

 are fed and cared for by the qiieen until they reach maturity. This first brood is com- 

 posed entirely of workers. They relieve the queen of the duties which pertain to this 

 caste, and from this time forth her only duty is to lay eggs. It is stated, however, by 

 some authors, that she continues to assist in the care of the young, though not in the 

 construction of the domicile. 



The nests of the social wasps are composed of a papery substance made from wood. 

 The wasps collect, with their mandibles, the semi-loosened fibres from the surface of 



el 



FIG. 660. Diagrams of wasp nests, a, Polybia sedula ; b, P. rejecta ; c, Chatergus apicalis ; 



d, Polybia ampullaria. 



weather-beaten wood, which, by mastication and mixing with a buccal fluid, is made 

 into pulp, easily moulded, and drying on exposure to air. The sides of unpainted build- 

 ings and of fence boards afford the chief supply in inhabited portions of the country. 

 If a wasp's nest be closely examined, the paper will be found to be streaked with 

 various shades of gray and brown, each little streak or blotch indicating the amount of 

 material brought at once by a single wasp. 



The essential part of a wasp's nest consists of a comb formed of hexagonal cells 

 similar in form to the cells of a honeycomb. It differs, however, in several important 

 respects from that of the hive-bee. The material from which it is composed is paper 

 instead of wax. The comb consists of a single layer of cells instead of two, and the 

 cells are usually vertical instead of horizontal. In some species the nest consists 

 merely of a single comb with one or more stems holding it in place. In others the 

 comb is enclosed in a spherical envelope with a small opening at the bottom. In the 

 more complicated nests there is a series of combs placed one below the other, and the 

 whole is enclosed in a spherical case made of many thicknesses of paper. The nests 

 are enlarged by adding cells to the edges of the combs, and room is made for these new 



