INSECTS 



matter of survival of the fittest, the roach, judged by 

 survival, must be a most fit insect. Its fitness, however, 

 is of a general nature; it is one that adapts the roach to 

 live successfully in many kinds of conditions and circum- 

 stances. Most other forms of mod- 

 ern insects have been evolved 

 through an adaptation to more 

 special kinds of habitats and to 

 particular ways of living or of feed- 

 ing. Such insects we say are 

 specialized, while those exemplified 

 in the roach are said to be general- 

 ized. Survival, therefore, may de- 

 pend either on generalization or on 

 specialization. Generalized forms 

 of animals have a better chance of 

 surviving through a series of chang- 

 ing conditions than has an animal 

 which is specifically adapted to one 

 kind of life, though the latter may 

 have an advantage as long as con- 

 ditions are favorable to it. 



The roaches, therefore, have sur- 

 vived to present times, and will 

 probably live as long as the earth is 

 habitable, because, when driven 

 from one environment, they make 

 themselves at home in another; but we have all seen how 

 the specialized mosquito disappears when its breeding 

 places are destroyed. From this consideration we can 

 draw some consolation for the human race, if we do not 

 mind likening ourselves to roaches; for, as the roach, 

 man is a versatile animal, capable of adapting himself to 

 all conditions of living, and of thriving in extremes. 



Fig. 6i. A young mayfly, 

 a water-inhabiting crea- 

 ture. (One-half larger 

 than natural size) 



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