PERFECT SOCIETIES OF INSECTS. 91 



When the population exceeds the produce of a coun- 

 try, or its inhabitants sulFer oppression, or are not 

 comfortable in it, emigrations frequently take place, 

 and colonies issue forth to settle in other parts of the 

 globe ; and sometimes whole nations leave their own 

 country, either driven to this step by their enemies, or 

 excited by cupidity to take possession of what appears 

 to them a more desirable residence. These motives 

 operate strongly on some insects of the social tribes. — 

 Bees and ants are particularly influenced by them. 

 The former, confined in a narrow hive, when their so- 

 ciety becomes too numerous to be contained conveni- 

 ently in it, must necessarily send forth the redundant 

 part of their population to seek for new quarters ; and 

 the latter — though they usually can enlarge theii^ dwell- 

 ing to any dimensions which their numbers may re- 

 quire, and therefore do not send forth colonies, unless 

 we may distinguish by that name the departure of the 

 males and females from the nest — arc often disgusted 

 with their present habitation, and seek to establish 

 themselves in a new one : — either the near neighbour- 

 hood of enemies of their own species ; annoyance from 

 frequent attacks of man or other animals ; their expo- 

 sure to cold or wet from the removal of some species of 

 shelter ; or the discovery of a station better circum- 

 stanced or more abundant in aphides ; — all these may 

 operate as inducements to them to change their resi- 

 dence. That this is the case might be inferred from 

 the circumstance noticed by Gould % which 1 have also 

 partly witnessed myself, that they sometimes transport 

 Iheir young brood to a considerable distance from their 



^ Gould, 42. 



