LIFE HISTORY OF INSECTS. 219 



nourishing character their larvae occupy six to 

 eight weeks between the egg and pupa. 



Wire worms and cockchafer grubs, which live 

 in the soil and feed on roots, have unfor- 

 tunately a larval life extending from one to 

 five years. 



There seems to be no part of plants and trees 

 that is free from insect attack. 



Weevils destroy seeds. 



The turnip beetle pounces upon the young 

 seed leaves directly they appear above ground. 



The saw fly larvae give to leaves a scorched 

 appearance. 



Some insects tunnel into the tissues of leaves ; 

 other insects cause the little gall swellings which 

 at certain years appear all over the leaf. 



The caterpillars of the cabbage butterfly riddle 

 leaves with holes, and cockchafers devour leaves 

 wholesale. 



Blossoms are destroyed by beetles and aphides 

 or green fly. 



Stems and woody trunks are attacked by the 

 bark beetles, goat moth, caterpillars, and other 

 borers. 



The wire worm is the chief enemy to the roots 

 of crops, but it has many helpers. 



Some insects confine their attacks to special 

 groups of plants, as the turnip fly to the turnip 

 group, namely, the cruciferous crops. 



