186 



AGRICULTURE 



Insect enemies. The insect enemies of the fruit gar- 

 den are of two types: the biting insects, or those that actu- 

 ally eat portions of the plant; such as the larvae of the 

 codling-moth ; and the sucking insects, or those that pierce 

 the fruit, leaves, or bark with sharp beaks or bristles, and 

 live off the juices of the plant. The latter group includes 

 various plant bugs, lice and scale insects. 



In general, the biting insects can be destroyed by spray- 



Apple clusters, on the left, with calyx lobes spread and in good 

 condition for spraying; on the right, with calyx lobes closed 

 and too late for effective spraying. 



ing with some poison such as the arsenical compounds, 

 which, if eaten, will kill them. The sucking insects can not 

 be destroyed in this way, since the poison does not penetrate 

 into the plant tissues whence they draw their food. For 

 this group it is necessary to use some preparation that will 

 either act on their bodies as a caustic, or that will smother 



