Insects and their world 



The nuptial flight of termites involves fully winged males and 

 females, which are produced in a nest or colony at intervals, and issue 

 in a swarm. Many are killed by birds or lizards, but the few that survive 

 cast their wings and go off in pairs to found a nest. Mating does not 

 take place in the air, but in a nuptial chamber that the insects construct 

 either in wood or in the ground. 



The eggs laid by the queen give rise to sterile males and females, 

 which act as workers to feed the colony, and soldiers to guard it. There 

 are a number of different forms of these, to which names are given. As 

 time goes on the abdomen of the queen becomes distended, the mem- 

 brane being stretched, and the abdominal plates widely separated 

 (Fig. 9), until the queen becomes a mere bag of eggs, with a small head 

 and thorax attached. A mature queen of some groups may lay several 

 thousand eggs a day, being fertilised at intervals by her consort male, 

 and storing the sperm in her spermatheca. 



At long intervals fertile males and females, with wings ('alate 

 reproductives ') are produced and swarm out of the nest, to pair off and 

 found new colonies. It is beUeved that the royal pair can Uve over a 

 long period of years, and if one of them dies, then a replacement, or 

 supplementary reproductive, makes its appearance. 



The termites are more difficult to study than the Hymenoptera, or at 

 any rate than the bees, and it is not known exactly how the workers 

 are able to produce fertile males and females in place of sterile ones. 

 By analogy with bees it is thought that changing the diet may be the 

 explanation. 



Termites are among the few insects that can digest cellulose, and so 

 are able to feed on the plant-tissue itself, and not only on its sugary 

 and starchy contents. That is why they are able to live on dead wood 

 and be so destructive to it. The digestion of the cellulose is in fact 

 carried out by single-celled animals called Protozoa, which live in the 

 intestine of the termite and pass on to it the chemical products of the 

 breakdown of the wood. 



Besides cellulose, termites eat other plant material, lichens and fungi. 

 Columns of workers come out at night, protected by soldiers, to collect 

 suitable food material and take it back to the nest. In addition, some 

 groups cultivate ' fungus -gardens ' inside the nest, where they grow their 

 own food. 



There is a good deal of passing on of food from one individual to 

 another, either from the mouth, mixed with saliva, or as faecal drop- 

 pings. The latter is the means by which the intestinal Protozoa are passed 

 on to other individuals. This resembles the mutual exchange of food 

 in nests of Hymenoptera, which Wheeler called *trophallaxis'. 



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