238 ANIMAL LIFE 



which it creeps over stones or plants. The pupal 

 skin now splits, and the fly emerges. 



Beetles. The life-histories of beetles offer another 

 simple example of metamorphosis. They fall into the 

 three epochs of larval, pupal, and adult existence. It 

 is with some surprise that we find in this order the 

 gradational mode of evolution superseded by this 

 abrupter succession of events ; for beetles bear the 

 marks of antiquity. They are in close touch with 

 the soil, their food consists largely of moulds and of 

 the organic substances, animal and vegetal, on which 

 fungi are flourishing. The majority are cryptic or 

 crepuscular, and only the more modified forms feed 

 on sap, pollen, or nectar between their flights in the 

 sun. But though the life-history of beetles has a 

 pupal stage of preparation for the life of maturity, it 

 is marked by a leisureliness that recalls the long 

 immaturity of the grasshopper and the dragon-fly. 

 The cockchafer is three years old when it emerges in 

 summer, some ground-beetles have an equally long 

 larval life, and stag-beetles six years. Moreover, the 

 larvae show few of those special adaptations that make 

 the caterpillars so attractive. They are usually six- 

 legged, spindle-shaped organisms, with powerful jaws, 

 but with no gracefulness of form or movement. Their 

 obscure life is reflected in their dull or fleshy tints. 

 They live for the most part on roots, fungi, wood, or 

 on other animals, and are among the scavengers of 

 the earth. The dor-beetles and the related scarabs 

 dig holes and provision the burrow for their young. 



