34 THE ECOLOGY OF ANIMALS 



generally found coyness in female insects during court- 

 ship (Richards, 1927), and special features found in 

 territorial birds). Such epigamic behaviour plays a 

 very important part in the lives of wild animals, 

 takes up considerable parts of their time during the 

 breeding season and sometimes outside it, and cannot 

 be left out of consideration from an account of the 

 organization of animal communities. For instance, 

 certain insects frequent certain habitats only in order 

 to carry out epigamic ' ceremonies ', and while there 

 form the food of other forms (cf. Richards, 1930). 

 The conditions necessary for the successful carrying 

 out of such courtship may also determine whether 

 a species can breed in a habitat, while the field 

 observation of such behaviour has a pecuUar fascina- 

 tion for many naturaUsts. 



The second type of iater-relationship concerns social 

 groupings and the development of castes. Wheeler 

 (1928) estimates that genuine social life has developed 

 independently in at least thirty different groups of 

 insects. It is most highly developed in the ants and 

 bees and termites (see Imms, 1931, in the present 

 series). Social life in ants has tremendously import- 

 ant effects upon the general organization of fife in 

 some animal communities, in relation to destruction 

 of many species of animals on a large scale, ' farming 

 habits ' with aphids, coccids, etc., other agricultural 

 practices, e.g. the growing of fungi for food, and 

 indirectly in the construction of large habitations in 

 which many other forms of animals live as guests 

 or parasites of varying degrees of dependence. Refer- 

 ence should be made to Wheeler (1922, 1928) and 

 Imms (1931) for fuller accounts of social insects and 

 to Alverdes (1927) for information both about insects 

 and about other groups. The chief effect of social 

 habits on the ecological organization of an animal 

 community is through the greatly increased power 

 that it gives one species over many others, with the 

 result that the social group sometimes becomes as 



