THE SOCIAL INSECTS 



higher social insects have lived in complex societies for at 

 least thirty times as long. Few biologists would care to predict 

 where we shall be when thirty million more years have 

 passed. H. G. Wells, in his story The Time Machine^ fore- 

 casts one possible result of such a period of evolution, 

 assuming that we have a somewhat ant-like future. Such a 

 course seems much less likely now than it may have done 

 fifty years ago. 



The efficiency of some of the different types of ant societies 

 can be judged by their success when in competition with one 

 another. The Argentine ant, a native of the southern part of 

 South America which has been accidentally introduced into 

 many parts of the world, is a good example, as Haskins has 

 shown. It is a small, fragile species with a soft, easily 

 damaged skeleton. The workers have no sting, but they can 

 produce a sticky, scented, anal secretion which may be of 

 some defensive value. It has now established itself in many of 

 the warmer parts of the world and in some, such as the island 

 of Madeira, it has completely eliminated the local ant fauna. 

 Though it cannot tolerate cool climates like ours, even in 

 the British Isles it has several times survived for some years 

 in the shelter of buildings. 



It seems to have two main advantages. First, the workers 

 forage in large groups which are capable of an unusual degree 

 of co-operation. Secondly, it has a specialised type of repro- 

 duction. The queens are small, hardly larger than the 

 workers, but there are many of them in each colony : they 

 have solved the difficulty of getting several egg-laying females 

 to tolerate one another. This means that it is very difficult 

 to destroy a colony, and that the queens are cheap to produce. 

 This type of organisation is very successful, but not very 

 mobile. The queens cannot found new colonies unaided and 

 the colonies reproduce by " budding ", the splitting off of 



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