THE SOCIAL INSECTS 



forms which use the grub to spin silk, the whole work of 

 the colony is done by adults, and by definition the form 

 and behaviour of these is in the main fixed for life. Though 

 there may be variation in fertility and changes in the size 

 of the abdomen, as in the queen legionary ant or the worker 

 honey-pot ant, the form of most individuals is constant and 

 none can alter parts of the body other than the abdomen. 

 In the termites, on the other hand, the individual is usually 

 capable of changing both its appearance and its functions 

 over a considerable period after it has begun to play an 

 important part in the life of the colony. This introduces the 

 possibility of " social regulation ", the moulding of the 

 individual to the needs of the community at any particular 

 moment. 



NESTS 



Termite nests often form a conspicuous feature of the 

 landscape in tropical regions. They vary much in shape and 

 structure, even within one group. They are built of earth, 

 of rotten wood, or of the insects' own excrement, or of a 

 mixture of these. Often a sort of cement is made of saliva 

 and clay, and this may set extremely hard. One of the diffi- 

 culties of preparing the site at Kongwa in East Africa for 

 planting ground nuts was the problem of removing the 

 numerous large termite nests. Often a nest required a large 

 charge of dynamite. 



Termites, apart from a few exceptional species, avoid all 

 contact with light and with the free air. Their nests are 

 therefore always closed. When the winged forms wish to 

 leave, or in species which send foraging columns into the 

 open, temporary exit-holes are made, but they are soon 

 closed again. A few species are known to carry their excre- 

 ment outside the nest and these also make temporary exits 



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