Saw-flies, Gall-flies, Ichneumons, etc. 505 



few days issue as winged wasps. They are exclusively workers. These 



FIG. 709. Vespa sp. a, worker; b, female or queen. (After Jordan and Kellogg; 



natural size.) 



workers now enlarge the nest, adding more brood-cells in which the 



queen deposits eggs. The bringing of 



food and care of the young now devolve 



on the workers. The new or second 



brood is also composed of workers only, 



and these immediately reinforce the first 



brood in the work of enlarging the nest 



and building new brood-cells. Thus 



through the summer several broods of FIG. 710. Two workers of the yel- 



workers are reared, until in the late sum- low-jacket, Vespa sp. (From life; 



, , , natural size.) 



mer or early fall a brood containing males 



and females as well as workers appears. The 

 community is now at its maximum both as re- 

 gards population and size of nest. In the species 

 (Vespa sp.) which make the great ball-like aerial 

 nests the community may grow to number 

 several thousand individuals. The males and 

 females mate (presumably with members of 

 other communities), but no more eggs are laid, 

 and with the gradual coming on of winter the 

 males and workers and many of the females die. 

 There persist only as survivors of each com- 

 munity a few fertilized females; these crawl 

 into safe places to pass the winter. Any 

 social wasp found in winter-time is thus, almost 

 certainly, a queen. Those of the queens which 



come 



FIG. 7ii.-Communal nest of ^ 111C Sttlc ^ thr U g h the lon g winter found 

 the yellow-jacket, Vespa sp. the communities which live through the follow- 

 (Much reduced.) ing season 



The social wasps of the genus Vespa, the familiar yellow-jackets and 



