THE YOUNG INSECT 15 



this is merely because its development is already complete. 

 We may compare the life of an insect to a long hill which 

 ends abruptly in a precipice. When the young insect 

 (usually termed a larva) hatches from the egg, it enters 

 upon a protracted period which it devotes almost exclu- 

 sively to feeding. Food is the key-note of its being, the 

 hinge upon which its every action turns. Then follows a 

 comparatively brief period of maturity, terminated by the 

 insect's death. The aquatic larva of the well-known 

 may-fly, for example, feeds voraciously for several years ; 

 whereas the adult insect takes no food at all, and lives 

 only for a few hours. Its jaws and digestive tract are 

 quite functionless — are reduced, indeed, to mere vestiges. 

 Of course this is an extreme case ; yet it serves to em- 

 phasize the fact that the life of a typical insect is sharply 

 divided into two periods — one long, the other compara- 

 tively short. In a sense, therefore, the young insect and 

 its adult form may be regarded as separate personalities, 

 each charged with distinct duties. The former under- 

 takes the task of storing up food material, while the latter 

 is concerned with courtship and parentage. Let us glance 

 once more at the case of the may-fly. We see a long 

 larval life entirely devoted to the production of an ephe- 

 meral being, incapable of feeding, whose one and only 

 duty is to reproduce its kind. Indeed, the final wdnged 

 state of the may-fly might long ago have fallen into obso- 

 lescence were it not for the fact that in this state alone 

 is reproduction possible. 



Among the more primitive insects the newly-hatched 

 larva is practically a miniature copy of its parents. 

 The baby cockroach, for instance, has an unmistakable 

 family likeness from the first, although it is almost 

 colourless and quite destitute of wings. Very soon 

 after hatching it casts its skin for the first time. A 



