272 FRUIT PESTS 



since the insects are extremely small and every portion of 

 the plant must be covered. 



Plant Lice or Aphids. Plant lice usually appear on 

 the foliage or young growths in the spring and early sum- 

 mer. Some seasons they are more prevalent than others. 

 These insects suck the plant juices, causing the leaves to 

 curl and become distorted. The green aphid attacks the 

 apple, pear, and plum trees, while the common black aphid 

 works on the cherry. The eggs are laid 

 on the branches of the trees in the 

 autumn, hatch in the spring, and the lice 

 locate upon the young shoots. The 

 woolly aphid attacks both the branches 

 and roots of the apple and is distinguished 

 from the others by having a conspicuous 

 Fig. 146. -An aphid. woolly covering The root-inhabiting 



variety of this insect does the most injury. Infected roots 

 become contorted and the tree sickens or dies. 



If the foliage is infected, it should be sprayed with 

 nicotine or strong tobacco tea before the leaves curl. The 

 root aphid is destroyed by the use of tobacco dust, four to 

 six handfuls of which should be spread on the soil and 

 thoroughly worked into it. The ends of the shoots of young 

 trees should be dipped into a pail of tobacco water. 



San Jose Scale. The San Jose scale is the most dan- 

 gerous insect pest of the orchard. All our common fruit 

 trees are subject to its attack as well as many of the small 

 fruits like the currant and gooseberry. It is found upon 

 the branches, leaves, and fruit of the tree and is usually 

 first discovered on the fruit during the harvesting period. 

 Here it causes red, circular discolorations, in the center of 

 which are the black scales. The insect is exceedingly dif- 



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