360 BOARD OF AGRICULTURE. [Pub. Doc. 



Thus far, however, these hopes have failed to be realized. 

 In fact, all of these enemies together fail to do more than 

 to somewhat check the rapid increase of the scale, which, 

 when present, requires treatment by man in addition, if the 

 infested plants are to be kept from entire destruction. 



Treatment. 



The methods of treatment for the San Jose scale success- 

 fully used on the Pacific coast have thus far failed in the 

 eastern United States, where they are " fatal to only a small 

 percentage of scales." Why this is the case it is difficult to 

 say. In California the treatment is applied some little time 

 before the rainy season, which gives an opportunity for its 

 action before being washed off by the rains. In the east, 

 however, this treatment must be applied at times when rains 

 are frequent, and it may be that in this fact is found the 

 reason why the treatment is a failure in this part of the 

 country. 



The San Jose scale is a sucking insect ; consequently, 

 neither Paris green, arsenate of lead or any of the so-called 

 "stomach poisons" are of the slightest use. The treat- 

 ment which will kill it must be something which kills by 

 coming in contact with it ; and as the insect, except in its 

 earliest stages, is covered by a hard scale, the treatment 

 must be by the application of some substance caustic enough 

 to eat or corrode the scale and penetrate to the body of the 

 insect beneath. Spraying with kerosene emulsion will kill 

 the young insects, of course ; but as these appear every few 

 days from some time in June until November, or even 

 December in some cases, this would mean that the infested 

 trees must be sprayed at least once a week during this entire 

 time, which is also the time during which it is most difficult 

 to reach all parts of the tree thoroughly, on account of the 

 foliage. Accordingly, treatment during the winter months 

 is the best. 



Destruction of Trees infested. 



In cases where the scale has just appeared, or but few 

 trees are infested, the cheapest and safest treatment is to cut 

 down and burn those trees. If a tree be thoroughly covered 



