222 THE BIOLOGY OF INSECTS 



well-known groups of Hymenoptera, the wasps, bees, and 

 ants. As previously mentioned, the societies of these 

 insects are in reality large, often immense, families, and the 

 family life of some wasps and bees has been described 

 in the preceding chapter. In a typical insect community 

 belonging to one of these groups, the vast majority of the 

 population are those modified females, known as " workers," 

 usually infertile and often in some way specialised for 

 carrying on the essential activities of the society. The 

 fertile females in a nest, actual or potential mothers, are 

 known as " queens." Among the greater number of 

 genera of wasps and bees, such as those mentioned in the 

 last chapter, the individual insects are all normal, fertile 

 females and males. There are no workers, and these insects 

 are commonly termed *' solitary " — a term that may be 

 considered not altogether appropriate, for though the 

 family does not grow into a great society, a number of 

 females of the same kind often make their nests close 

 together, as with Synagris among the wasps and Andrena 

 among the bees ; but although scores or hundreds of such 

 wasps and bees have their nests close together there is no 

 co-operation between the diiferent mothers or their families. 

 The hymenopterous society being a very large and more 

 or less specialised family, we expect to find some indication 

 of its mode of development from an ordinary family, and 

 Wheeler suggests that the habits of certain wasps indicate 

 stages of transition between the " solitary " and " social " 

 way of life. F. X. Williams (19 19) has shown how some 

 species of the eastern tropical Stenogaster are solitary while 

 others approach the social habit, as they construct nests 

 of several chambers, sometimes enclosed in an envelope, 

 the mother feeding a number of larvae at the same time, 

 sealing up the chambers when they are fully fed, and sharing 

 the nest with her daughters when these have attained the 

 adult condition. None of the Stenogaster females, however, 

 appear to be infertile or to be in any way specially modified 

 as workers ; the adult inhabitants of the nest are relatively 

 few in number, and it is doubtful how far the daughter- 



