32 INSECTS NOXIOUS TO AGRICULTURE. 



The object of the milk is not only to lessen the 

 injurious qualities of the kerosene, but also to induce 

 it to mix more freely with the water ; but it is the 

 oil alone which destroys the insects and their eggs. 



(c.) Kerosene and soap. When milk is not obtain- 

 able, or too dear, nothing is so excellent as this mix- 

 ture. Soap itself (see below) is a useful insecticide, 

 and in combination with kerosene includes the good 

 qualities of both substances. The cheapest possible 

 qualities of soap will do. The mixture, which is, 

 even more than the last, purely mechanical, must be 

 made first of all an " emulsion." The American 

 experiments result in the following recipe and method 

 of using : 



Formula : 



Common soap ... ... ... ^lb. 



Kerosene 2 galls. 



Soft water 1 gall. 



Dissolve the soap in the water heated to boiling, 

 then add the kerosene, and churn the mixture until 

 a creamy fluid results which thickens on cooling. 

 Dilute with nine or ten times the quantity of water : 

 the quantities given above will make about thirty 

 gallons of liquid. Whale-oil soap, soft-soap, or any 

 other kind will do. As with the milk emulsion, 

 apply in the form of the finest spray for evergreens 

 (Riley ; Hubbard ; Personal experiment) . 



(d.) Kerosene and oil. Castor-oil, linseed-oil, whale- 

 oil, may be used. A mixture of this kind, in the 

 proportion of 1 part kerosene to 3 or 4 of oil, has 

 been found very efficacious for apple- and other fruit- 

 trees attacked by the common apple-scale (Myt. po- 

 morum). But, as observed above, the mixture must 

 not be laid on too thick. Thinly brushed all over 

 trunk and branches, at dead of winter, it has been 

 found quite successful in destroying both insects and 

 eggs, without injury to the trees (Personal experi- 

 ment) . It would probably not answer for evergreens, 

 on account of expense. 



On the whole, it may be said that, as far as cer- 

 tainty can be attained in the matter, there is no sub- 



