Diseases 269 



care being taken not to damage them in the 

 operation, by roughly handling the leaves. 

 Whichever of these two methods is employed, 

 the wash should be carefully rubbed over the 

 entire surface of the leaf with a piece of 

 sponge, or soft cloth. When the liquid is 

 applied as a spray, the force with which it 

 strikes the surface of the leaves enables 

 it to penetrate the waxy secretion covering 

 the insect, but when dipping or washing- 

 is resorted to, it becomes necessary to assist 

 the penetration of the liquid in the manner 

 indicated. 



If the young trees in the field are attacked 

 by these insects to such an extent as to render 

 it desirable to apply an insecticide, it will 

 probably be found advantageous to use a 

 knapsack or a barrel spraying machine, while 

 the latter would also be useful for spraying 

 older trees. 



Among commercially valuable trees in the 

 Philippines, according to Charles S. Banks in the 

 Philippine Journal of Science, vol. i, Nos. 2 

 and 3, 1906, few are attacked by so small 

 a number of insect pests as the coco-nut ; 

 but, on the other hand, the destructive action 

 of this limited number is very great. The 

 trunk of the coco-nut does not have its 

 important conducting tissues in or immediately 

 under the bark, as is the case with cacao, 

 coffee, or the mango. For this reason, even 

 though the tree were completely girdled, 



