SCALE-INSECTS. 



31 



cineus (Alderton) ; in Nelson it is said to be used 

 beneficially against leery a purchasi. It does not, 

 however, kill the eygs ivith certainty (Personal experi- 

 ment). Applied warm, and properly diluted, it may 

 be recommended as a good remedy ; but applications 

 of it should b^ repeated. 



9. Kerosene. Seemingly the most valuable of all remedies, 

 when properly applied. " Almost the only substance 

 which will certainly kill the eggs without at the same 

 ; time destroying the plant " (Hubbard) . 



But the application of this remedy must be care- 

 fully performed. Some trees may endure it without 

 injury, even undiluted or unmixed ; but this is 

 scarcely to be expected, and the oil should therefore 

 be applied in some mixed form. Also, it is important 

 to remember that a hot sun increases the injurious 

 effect of kerosene ; consequently winter, or cloudy wea- 

 ther, should be chosen for its employment. 



(a.) Pure kerosene. As just stated, it is probably 

 not advisable to use this. Still, " a young shoot of 

 orange, not more than fourteen days old, was un- 

 injured by an application of pure kerosene which 

 thoroughly wet every leaf ; " (Comstock) ; and Le- 

 canium hesperidum on ivy, similarly treated, was de- 

 stroyed, without injury to the plant (ibid.). 



(b.) Kerosene and milk. An excellent mixture, if 

 milk can be obtained cheap (Riley ; Hubbard ; 

 Comstock) . It must be applied in the form of an 

 " emulsion," sprayed over the tree or brushed on the 

 bark. Hubbard gives the following directions for 

 use : Heat the milk nearly to boiling-point and mix 

 with double the quantity of kerosene ; churn violently 

 from ten minutes to half an hour, according to tem- 

 perature, until a creamy thick fluid is obtained ; 

 dilute this with nine or ten times the quantity of 

 water. The mixture is of course purely a mechanical 

 one, as far at least as the water is concerned, and it 

 must be kept constantly stirred, to prevent the sub- 

 stances from separating from the water. For ever- 

 green trees impel the mixture on leaves and branches 

 in the finest possible spray. Sour milk is as useful as 

 fresh. 



