THE SOCIAL INSECTS 



different colonies fight bitterly, and colonies of the honey bee 

 can be combined in one hive only by devices which enable 

 them to acquire a common smell. It is very unusual, perhaps 

 even unknown, for separate colonies to combine in natural 

 conditions. 



Thus while the insects have species and families or colonies, 

 they do not have tribes or nations. The failure to develop 

 co-operation on the larger scale which occurs in man may 

 be partly due to their much higher fertility. In man, several 

 families had to combine to form a group big enough to master 

 a mammoth, let alone build a cathedral. But insect families 

 are so much larger that there would never have been the 

 same advantage in combining with strangers. 



When two insects meet they do not normally fight unless 

 one forms the natural food of the other. What might be 

 called nasty aggressive behaviour, worthy to be compared 

 with our own, is always in essence the fight for an ovipositi on- 

 site. Some flies which lay their eggs in fruit will knock other 

 females off in order to get their place on the fruit, but 

 aggression is usually found only in females with a nest to 

 defend, and they will drive off any other insect which hap- 

 pens to come too close. 



Members of one colony would, therefore, live together 

 amicably if they all smelt the same and if there were only one 

 ovipositing female. In itself, this would not lead to much in 

 the way of co-operation, and probably at first the nest would 

 be an aggregation of the single nests of each individual. 

 Something like this seems to be still true of Halictus. But 

 if one started with an insect which already had behaviour 

 as elaborate as that of the solitary Ammophila, it is reasonable 

 to think that the great advantages of co-operation within the 

 family group would provide plenty of opportunities for 

 selection. A great deal of the social co-operation of insects is 



204 



