INSECTS AND INSECTICIDES. 



leaves or on growing shoots. These insects multiply very 

 rapidly, but fortunately for the grower the hot summer climate 

 of California prevents long duration of their attack and there 

 also exist in California hordes of natural enemies which attack 

 them shortly after their appearance and soon reduce their 

 numbers. 



In favorable seasons, however, plant lice become a very seri- 

 ous pest and artificial means for fighting them have to be 

 resorted to. Near y all varieties of fruit trees are attacked by 

 them and a great many of our early fruits are rendered unsal- 

 able by the abundance of honey-dew exuded by these insects. 



The principal known species are: 



Woolly Aphis {Schizoneura lanigera). — This little insect 

 secretes a white cottony mass about its body and infests both 

 the roots and the 

 branches of apple 

 trees. Its presence 

 can be readily de- 

 tected by this white 

 cottony mass, and 

 upon close examina- 

 tion the brownish- 

 pink lice are found 

 under the cotton. The 

 root form causes great 

 damage to the tissues of the roots by forming swellings or 

 galls, giving an unhealthy growth, which soon kills the small 

 roots. As the root-infesting form is by far the most destruc- 

 tive, it is important that remedial measures should be directed 

 against it. By eradicating the root form in winter a great 

 reduction in the branch or aerial form follows, but it can be 

 readily understood that this underground form is extremely 

 difficult to combat. 



Early in the fall dig a trench around the tree, uncovering 

 the crown roots as much as possible ; in this trench place one 

 or two shovelfuls of unslaked lime, according to the age and 

 size of the tree; add enough water to slake the lime, and cover 

 up with earth. The rain will keep carrying the lime to the 

 roots and reduce the pest. As a substitute for the unslaked 

 lime, gas lime is very often used, but great caution must be 



Woolly Aphis of the apple (ScMsOTieura 

 lanigera, Hausm.) 



