217 



CHAPTER X 



THE LIFE-HISTORIES OF INSECTS 



OF all the impressive actions that insect life presents, 

 those connected with the welfare of their young and 

 with their life-history are the most important, and 

 in fact it is largely by their other-worldliness that the 

 group has risen from its obscure beginnings and poor 

 relations the spring-tails, silver-fish, and centipedes 

 to range after range of dominance in the kingdoms of 

 the air. Beyond the usual demands for racial welfare, 

 such as we meet with in many other highly organised 

 and aerial creatures spiders and birds, for example, 

 there has evidently been, in the case of insects, some 

 factor at work which has led to this elaboration of 

 nurseries, this preparation of special foods, this 

 sunlit , devotion to the needs of a progeny that its 

 mother may never see. 



Such a factor we may see in the influence of climate. 

 Insects are border folk. They are the offspring of 

 earth and air. Great as are their powers of adaptation, 

 they have failed to adjust and maintain the tempera- 

 ture of the body without direct reference to that of 

 their surroundings. Hence their vitality rises and 

 falls with the thermometer, and the more exaltedly 



