92 THE LIFE-STORY OF INSECTS [CH. 



the Termitoxeniidae, curious, degraded, wingless 

 ' guests ' of the termites, or ' white ants,' lately made 

 known through the researches of E. Wasmann (1901). 

 Here the individual is hermaphrodite a most ex- 

 ceptional condition among insects and lays a large 

 egg, whence is usually hatched a fully- developed 

 adult! Here then Ave find that all the early stages, 

 usual in the higher insects, are omitted from the life- 

 story. 



Interesting comparison may be made between the 

 total duration of various insect life-stories. To some 

 extent at least, the length of an insect's life is cor- 

 related with its size, its food, the season of the year 

 when it breeds. Small insects have, as a rule, shorter 

 lives than large ones; those whose larvae devour 

 highly nutritive food generally develop more quickly 

 than those which have to live on dry, poor, sub- 

 stances; life-cycles follow one another most rapidly 

 in summer weather when temperature is high and 

 food plentiful. 



In early chapters we have already noticed the 

 long aquatic life of the larva and nymph of a 

 dragon-fly, relatively a large insect, and the rapid 

 multiplication of the repeated summer broods of 

 virgin aphids (p. 18). Within the one order of the 

 Coleoptera it is instructive to compare the small 

 jumping leaf-beetles, the 'turnip-flies' of the farmer, 

 whose larvae mine in the green tissues, and complete 



