172 



Elementary Principles of Agriculture 



well marked with dots and lines along the bodies, that are 

 characteristic for each species. After a time they leave 

 the tree and each individual spins a paper-like case, 

 called a "cocoon," in some sheltered place. The adult 

 moth emerges from the cocoon in a few weeks, and lays 

 the eggs as mentioned above. These changes may be 

 observed by bringing the almost mature caterpillars into 

 wire-screened cages. These caterpillars are attacked by 

 many insect parasites, snakes, frogs, and particularly by 

 birds. The orchard should be inspected 

 in the early spring for webs. 



238. "Wire- 

 worms" are very 

 common in fields. 

 They are the larval stage of 

 various species of night-fly- 

 ing beetles, such as the click- 

 beetles. The adult lives on the 

 nectar obtained from flowers 

 while the larval stage lives in 

 the ground and thrives on the 

 roots, leaves, and stems of 

 young plants. 



239. Plant -lice, or Aphids, 

 are common everywhere. There 

 are many kinds, and all are 

 quite small. Plant-lice are soft- 

 bodied, usually green, like the 

 "green bug," but some forms 

 are colored red or black or 

 Fig. 109. A corn-plant growing other color. Most of them are 



in a root-cage infested by wingless, though SOHie of them 

 wire-worms and click-beetles. D . 



After comstock. will have two pairs of transpar- 



