94 INSECTS AFFECTING THE ORANGE. 



Soap and Kerosene Emulsions. The difficulty of obtaining fresh milk 

 in Florida, and the cost of condensed milk, have made a cheaper substi- 

 tute desirable. This is found in a solution of soap, which forms with 

 kerosene an equally good emulsion. The quantity of soap used in so- 

 lution need not exceed one-quarter of a pound to, one gallon of water, 

 but stronger soap solutions are required to form a permanent emulsion. 

 The percentage of kerosene may also be varied greatly. But emulsions 

 containing over 80 per cent, of the oil have too light a specific gravity 

 and are not readily held in suspension in water. On the other hand, in 

 the process of ernulsifi cation, kerosene loses a portion of its value as an 

 insecticide, and emulsions containing less than 30 per cent, of the oil, 

 although they do not at all, or only very slowly, rise to the surface when 

 diluted with considerable quantities of water, are nevertheless too much 

 weakened for effective use against Scale-insects. 



The following formula is considered the best for general use. It 

 gives a wash of sufficient strength to kill the eggs of those species of 

 Scale-insect which are commonly found in Florida, although in dealing 

 with some of the Aspidiotus scales a somewhat stronger emulsion may 

 be required. 



FORMULA : 



Kerosene 2 gallons=67 per cent. 



Common soap or whale-oil soap . J pound ) ,> Q ^ 



/ :=oo uei cent/. 

 Water 1 gallon ) 



Heat the solution of soap and add it boiling hot to the kerosene. 

 Churn the mixture by means of a force-pump and spray-nozzle for five 

 or ten minutes. The emulsion, if perfect, forms a cream, which thick- 

 ens on cooling, and should adhere without oiliness to the surface of 

 glass. Dilute before using, 1 part of the emulsion with 9 parts of cold 

 water. The above formula gives 3 gallons of emulsion and makes when 

 diluted 30 gallons of wash. 



Necessary precautions in the use of Kerosene. A reckless use of any 

 penetrating oil upon plants cannot fail to prove detrimental. Kero- 

 sene is, however, much less injurious than the lighter oils, naphtha, 

 benzine, &c., with which, in a crude state, it is associated. The refined 

 oil, such as is commonly used for illuminating purposes, is safer, and 

 should always be used in preference to the lower grades, which contain 

 a large admixture of other oils exceedingly deadly to vegetation. 



Effect of Kerosene upon the Orange. Although the action of kerosene 

 proves more injurious to some plants than to others, a healthy orange 

 tree is but slightly affected by it, and will even support without serious 

 injury applications of the undiluted oil if judiciously made, i. <?., applied 

 in fine spray and avoiding exposure of the plant to hot sunshine or to 

 frost before the oil has evaporated. Unhealthy trees and trees suf- 

 fering from the attacks of Scale-insects receive a shock more or less 



