i>30 Report of the Depa-rtment of Entomology oe' the 



Caution.— Gyamde of potassium is a deadly poison and hence 

 should be properly handled and labeled. When exposed to the 

 air for a few hours it absorbs moisture; it should therefore be 

 kept in a tight box in a dry place. Hydrocyanic acid gae is also 

 very poisonous and hence, when fumigating, the operator should 

 be careful that the tent or box has aired for a few minutes before 

 he goes inside. 



SPRAYINQ 



A large number of mixtures have been, tested with a view to 

 ascertaining a satisfactory wash to destroy the. scale. At present 

 three are considered the most satisfactory here in the East, 

 namely, kerosene oil, crude petroleum and whale-oil soap solution. 



A discussion of kerosene oil is given in the first part of this 

 bulletin. 



Crude petroleum. — Crude petroleum can be obtained from any 

 dealer in kerosene oil. The quality that seems to determine its 

 value as a safe insecticide is. its specific gravity which should not 

 be less than 43° (Beaum«5 oil scale) at 60° F. Oils of lower 

 specific gravity have been found to be more dangerous to the 

 trees. 



Method of application. — Crude petroleum may be applied pure 

 or mixed with water by means of a machine especially designed 

 for the purpose. In either case care should be taken not to apply 

 too much. The object of the spraying should be to cover every 

 part of the tree above ground with as thin a film of oil as 

 possible. If it is mixed with water by means of the pump, use 

 at least 40 parts of oil to each 60 parts of water making a mix- 

 ture containing 40 per ct. oil. 



When to apply. — Late winter or early spring is probably the best 

 time to apply the oil but more experiments are needed to deter- 

 mine this point. In any case it will be better not to apply it 

 after the buds have begun to swell; for although this has been 

 done in some cases without apparent injury, in others it has 

 ruined the trees. Summer application should be avoided. Care 

 should be taken not to put too much on the trees and to make 



