16 BULLETIN 645, U. S. DEPARTMENT OF AGRICULTURE. 



correct time for its application varies with the appearance of the 

 maximum number of the rust mites. It should be applied before the 

 mites get very abundant and before any russeting appears. It will 

 also kill some scales and white flies, but is not of great value for 

 that purpose. 



III. Paraffin-oil emulsion; Government formula, 1-66, or 1 per 

 cent of oil. August 25 to October 31. — This is the second spraying 

 for white flies and scale insects. The object of spraying at this time is 

 to kill the white-fly larvae which are the progeny of the third and 

 last brood. It is this brood that causes nearly all the damage from 

 the white flies, and the earlier they are killed the better it is for the 

 trees. This spraying also will remove the sooty mold from the trees 

 and a sufficient amount from the fruit to permit the fruit to be col- 

 ored up by the sun. Soda-sulphur, ISO, may be added to this spray- 

 ing to increase its effectiveness in killing rust mites. 



IV. Lime-sulphur solution, 32 z Bourne, 1-50 to 1-75. November 

 (/r December. — The object of this spraying is to kill rust mites, and 

 it may or may not be necessary, depending on the abundance of the 

 mites. 



It may be necessary to spray for rust mites before Treatment I 

 is given. This is especially the case with grapefruit in the more 

 southern counties. In case the red spider becomes abundant enough 

 to cause injury, an application of lime-sulphur solution should be 

 given. In case of heavy scale-insect infestation it may be necessary 

 to spray three times with the oil sprays, in which case the treatment 

 can be given in midsummer or in winter. If the red scale is very 

 abundant, two sprayings with the oil emulsions' should be given at 

 intervals of about a month. 



The paraffin-oil emulsion may be made according to directions 

 given in Circular No. 168, Bureau of Entomology. 



In addition to the foregoing there are three highly satisfactory 

 miscible-oil sprays on the market in Florida. 



The soda-sulphur solution is made according to the standard 

 formula : 30 pounds of sulphur, 20 pounds of caustic soda, and 20 

 gallons of water. This tests about 16° Baume and may be used 1-40 

 instead of lime-sulphur solution, but it is not so effective in control- 

 ling rust mites. It has an advantage over lime-sulphur solution in 

 that it mixes readily with the oil emulsions. 1 



COST OF SPRAYING. 



The cost of spraying depends upon many different factors, such as 

 the size of the trees, nearness to water, convenience of operation, 

 type of' spraying outfit employed, insecticide used, and character of 



*For directions for making lime-sulphur solution see Farmers' Bulletin 908. 



