INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 469 



sulphur solution to the two hundred gallons of water in the spray 

 tank. This spray is excellent for the red spiders on almond and citrus 

 trees. Minus the lime-sulphur solution it is a very effective spray 

 for the two-spotted mite (Tetranychus telarius) on hops. 



No. 2. (Iron Sulphide.) 



Water 200 gallons 



Flour paste, S pounds flour in S gallons water 



Lime-sulphur solution 21 gallons 



Iron sulphate 4 pounds 



This spray is mixed as the preceding, and the iron sulphate after 

 being dissolved is added directly to the diluted mixture in the tank. 



The above spray is especially recommended for late summer spray- 

 ings for red spider on almond and citrus trees, but should not be 

 applied to fruit trees just before the fruit is ready to pick, as the 

 fruit might be stained. 



LIME-SULPHUR IN COMBINATION WITH OTHER SPRAYS ?2S 



Lime-sulphur may be used in combination with tobacco sprays and 

 applied with safety on citrus trees prior to fumigation. It should 

 not be combined with Paris green, acid lead arsenate, zinc arsenite, 

 oil emulsions and soaps. With neutral lead arsenate, however, no 

 damage may result. 



EMULSIONS AND MISCIBLE OILS 



Emulsions are oil sprays in which soap is most frequently used as 

 an emulsifying agent. They have a high power of penetration and a 

 rapid and even distribution over the sprayed surface. With ordinary 

 care they may be readily made at home and are very valuable as 

 insecticides. 



In the miscible oils the emulsifier is incorporated in the oil. The 

 proportions must be very exact and vary according to the variation 

 in the composition of the oil and other ingredients, and is therefore 

 not practical to be made at home. The miscible oil sprays are the 

 highest type of emulsions and are almost universally employed for 

 commercial purposes. 



KEROSENE EMULSION 



There are two general types of kerosene emulsion, as follows : 



Cook Emulsion. — In this emulsion there is a larger amount of soap. 



It is the easiest to make, slightly more expensive and usually about 



as effective if made with a good grade of fish oil soap. The general 



formula is 



Fish oil soap 1 P°" n < 1 



Kerosene i gal on 



Water 2 gallons 



This was the first attempt at making an emulsion of Ibis type and 

 was a great discovery in insect control. It was invented by Dr. A. J. 

 Cook, the present State Commissioner of Horticulture. 



Riley-Hubbard Emulsion.— In this emulsion the proportion of soap 

 does not vary far from \ pound to a gallon of oil. It requires v< r\ 



