338 TEXTBOOK OF ZOOLOGY 



winter. Some of the larvae spun their cocoons in the vials while 

 others had already done this before being removed from the ground. 

 The room in which they were kept was cold, the temperature some- 

 times going slightly below the freezing point of water. About the 

 last of May the specimens were removed to the Brigham Young 

 University where they were kept on the writer's desk. The adults 

 emerged fully developed about the middle of July. One female 

 was kept in a breeding cage and fed on a syrup of cane sugar and 

 distilled water. 



"It is thought that under natural conditions the insects emerge 

 somewhat earlier in the summer than was indicated by the arti- 

 ficially reared specimens since they have been observed to be very 

 active even during the early part of May. It seems evident that 

 these early wasps build their nests in the spring and that their 

 young emerge during the same season. Only the individuals nest- 

 ing in the late summer spend the winter in the larval stage." 



The social wasps, belonging in the genera Vespula, Polistes, and 

 Polyhia, of the family Vespidae, start new colonies each spring from 

 overwintering queens. After the nests are built and the eggs begin 

 hatching, the queen feeds the larvae until they are completely de- 

 veloped. These workers then come to the aid of the exhausted 

 founder of the colony by taking over the enlarging of the nest and 

 the feeding of the larvae and the queen. The queen's only duty now 

 is to lay eggs. It will be noted that the Vespidae attend their young 

 by gathering food and feeding them; also that in turn the adults 

 may feed upon the saliva of the larvae. Wheeler believes that the 

 exchange of food in many of the social insects, which he chooses to 

 call "trophallaxis," has been the source of the social habit. 



In the family Bremidae, the bumblebees also start a colony in the 

 spring by overwintering queens seeking out an unoccupied mouse 

 hole or some other suitable hole in the ground. The queen gathers 

 pollen and nectar with which she fills a few cells. She then deposits 

 an egg in each cell and waits for them to hatch and develop into 

 workers. The workers assist in building and feeding the colony. 

 When the winter comes on, the queen, workers, and males die, leav- 

 ing only the females, which developed late in the summer and which 

 hibernate, to carry on the life cycle. All this is very similar to the 

 life habits of the social wasps. 



