THE SOCIAL INSECTS 



sometimes with bamboo runways from trunk to trunk. The 

 ant is stated to kill many caterpillars and to drive away 

 various beetles and bugs. 



The fact that ants feed on the sweet, liquid excreta of 

 aphides and mealy-bugs has been known for at least two 

 hundred years. Linnaeus, indeed, said that aphides were 

 ant-cows. Ants often keep certain species in their nests. 

 Many years ago Sir John Lubbock showed that ants collect 

 the eggs of the bean aphis in the autumn and in the spring 

 plant them out again on the food-plant. But the relations 

 between the two sorts of insects have hardly been studied 

 experimentally. It is still doubtful in most cases how far the 

 ants protect their cows from enemies. Apart from a good 

 deal of practical information of the type quoted from 

 Zimmermann's work, we do not know very much more of 

 the relations between the two sorts of insects than Sir John 

 Lubbock did. The absence of a detailed experimental study 

 is felt in the same way in a great many other facets of ant 

 life. 



THE FOOD OF ANTS 



The methods by which ants provide themselves with food 

 are analogous to three types of human culture recognised by 

 anthropologists, namely, hunters, food-gatherers, and agri- 

 culturists. Many ants, especially those which in structure 

 most resemble the non-social wasps, are purely hunters. 

 They catch and kill insects or other small animals. As a rule, 

 these are brought home whole and then cut up, to be divided 

 amongst the members of the colony. Often all available prey 

 of the right size are captured; less commonly, an ant may 

 specialise on a particular sort of prey. The American Lepto- 

 genys, for instance, catches mainly wood-lice. Most of the 

 hunters have a well-developed sting. 



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