THE WAR ON INSECTS 287 



sion stands to this very day, much the same as Mr. 

 Hubbard worked it out. 



Kerosene 2 gallons 



Water i gallon 



Hard soap \ pound 



Shave the soap fine and dissolve in boiling water; 

 warm the kerosene and add to the boiling suds; churn 

 with a force pump by pumping back into the pail 

 through a fine nozzle until a thick white cream is formed. 

 This hardens into a butter-like mass when cold and 

 may be diluted to any desired extent with water. If 

 both kerosene and suds are hot, five minutes' churning 

 will bring the proper combination. In making and 

 diluting the emulsion, soft water should be used and 

 only a little water should be mixed in at first to get 

 the butter into soluble form. A well-made emulsion 

 will keep for weeks in a dark cool place; but event- 

 ually the oil will separate and come to the top. 



Diluted with from twelve to fifteen times its own 

 bulk of water this is an excellent summer remedy for 

 plant lice, young leaf -hoppers, mites, thrips and other 

 insects liable to be killed by contact poisons. The pene- 

 trating qualities of the oil and clogging effect of the 

 soap are combined; but the soap prevents the rapid 

 evaporation of the kerosene, holds it longer in actual 

 contact with the vegetation to which it is applied, and 

 thereby increases its danger. Most plants will stand 

 an application of i to 15; few plants will safely stand 

 anything stronger than i to 10, and i to 12 is the more 

 usual limit. As a summer wash against scale larvae 

 the i to 10 mixture is an excellent combination on all 

 save stone fruits, and even i to 15 must be carefully 

 used on such. For winter work it is not advised, because 

 at a dilution strong enough to kill scales, it is actually 



