170 AMERICAN HYMENOPTERA. 



ber of cells in a nest varies with the size of the colony, and they are 

 so arranged that the open end is generally downward. The nests 

 of Polistes and Polyhia contain but one layer of cells, while those 

 of Vespa may have several layers, one above the other, with a nar- 

 row space between them. The nests of Vespa and Polybia have 

 the cells surrounded more or less completely by a paper covering, 

 while the cells of Polistes are not enclosed. The nests are all made 

 by a single colony in one season and all but the fertilized females 

 perish. Late in the Fall, after all the flowers are gone, if there are 

 any larvpe or partly grown wasps in the nest, it is said that they are 

 stung to death by the workers, who seem to realize that they would 

 die from the cold and starvation if this was not done. 



At the approach of Winter the fertilized females crawl into some 

 sheltered place and remain in a dormant state till the warm weather 

 in the Spring awakens them from their sleep. They at once con- 

 struct a nest with ten or more cells, lay an egg in each, and when 

 the larvse hatch they feed and care for them until they transform 

 into perfect insects. This first brood consists of workers only, and 

 these at once take up the task of enlarging the nest and caring for 

 the larvse ; for after this first brood has developed the female does 

 nothing but lay eggs. In the care of the young and the preparation 

 of their nests, the wasps very closely resemble the honey bee in its 

 habits. The workers are undeveloped females produced, according 

 to some authorities, by the amount and quality of the food given to 

 the larvae. Later in the season the females lay eggs which develop 

 into perfect males and females; these mate, the males and workers 

 die, and the females hibernate through the Winter. 



Dalla Torre gives a complete synonymy of all the species of tliis 

 family in his " Catalogus Hymenopterorum," vol. ix, and I have 

 therefore omitted all synonymy from this paper. 



General Characters of the Vespin^. 



The Vespinse are easily determined by having the wings folded 

 longitudinally w^hen at rest, the prothorax prolonged backward to 

 the base of the wings, eyes reniform, and intermediate tibiae with 

 two apical spurs. The males have thirteen segments in the antennae 

 and seven in the abdomen, while the females have only twelve seg- 

 ments in the antennae and six in the abdomen. The workers resem- 

 ble the females, but are generally much smaller. 



