46 



two pounds of oil is about three gallons, so that a full pint, or a little 

 over, may be considered the equivalent of a pound of oil. If a slight 

 excess of soda is used no harm will be done. This makes a soft 

 soap, but though when wann it stirs readily, when cold it forms a 

 stiff, cheesy mass. The soap made according to this formula is 

 stronger than most of the fish oil soaps on the market, and, as against 

 most green plant lice, may be used at the rate of one pound in seven 

 gallons of water. After it has been tested and the proper strength 

 for the different insects has become kno^vn to the user, it may be 

 relied upon to do the same work every time when made in the same 

 way. It is, of course, possible to make smaller quantities if desired; 

 the proportion being held carefully. Where it is necessary to sum- 

 mer-spray shade trees to kill scales or plant lice, this will prove the 

 cheapest and most reliable contact poison that can be used. 



Where the San Jose scale must be dealt with in the garden, there 

 is, perhaps, no better material on the market at present than "Kill- 

 0-Scale." This is a preparation of petroleum made soluble in water 

 and is one of the most active contact insecticides that we have. Any 

 other soluble petroleum would probably answer as well, and while 

 these preparations are rather expensive, they have the advantage of 

 being always ready and requiring nothing except a simple, dilution 

 with water when the application is to be made. 



Tobacco has been already referred to in connection with the treat- 

 ment of plant lice and its range of usefulness is there explained. 



For the gardener arsenate of lead and fish oil soap are really all 

 that are necessary. When large trees are to be dealt with, Paris green 

 may be substituted for the arsenate of lead, although the latter is 

 preferable, and fish oil soap or soluble petroleum will prove most 

 useful where contact insecticides are needed. 



Undiluted crude oil has been referred to and is the most effective 

 contact insecticide that we have. Unfortunately, its use is attended 

 by considerable danger to the tree if it be not carefully applied. 

 Nevertheless it is sometimes advisable, or even necessary, to employ 

 it, and in such cases danger may be reduced to a minimum — first, 

 by using oil having a specific gravity of at least 43° on the Beaume 

 scale — the insecticide oil supplied by the Standard Oil Company 

 is such an oil; second, have the oil slightly warmed, say 70° to 80°, 

 so that it will spread well; and, third, apply in a very fine spray, 

 just enough to cover. Applied with an atomizer, the oil is almost 



