366 



GENERAL SCIENCE 



FIG. 327. The San Jose Scale. 



increase in number they form a thick layer of scurf, 



which is readily removed with some sharp instrument. 



They suck the sap and thus 

 weaken the tree by withdraw- 

 ing the food that the tree re- 

 quires. In the spring the 

 mature female scales give birth 

 to about four hundred young. 

 These soon fasten themselves to 

 the bark of the tree and begin 

 to suck the sap and grow the 

 scale which covers them. The 

 female scales are without wings, 

 but the male scales develop 

 wings and are able to fly about. 



The best treatment for them is lime-sulphur spray. 



Figure 328 shows the effect of this scale on the pear. 

 The Codling Moth. Millions of dollars worth of 



fruit are annually destroyed by this pest. It lays its 



egg on the young apple. When the 



larva hatches, it eats its way into the 



apple. Young apples thus affected 



usually fall before they are very large. 



The way to. kill the codling moth is to 



have some poison on the apple ready 



for the first meal of the larva. This 



can be accomplished by spraying with 



arsenate of lead or some other poison 



just as the petals are falling from the 



blossom. 



The Chinch Bug. The central states 



of the middle West are often infested with the chinch bug 



(Figure 329). These insects attack the grain plants such 





Ohio Agricultural Experi- 

 ment Station. 



FIG. 328. The San 

 Jose Scale on a Pear. 



