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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. 
Ill. Parajfin-ou 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 larvee 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, 1-50, may be added to this spray- 
ing to increase its effectiveness in killing rust mites. 
IV. Lime-suiphur solution, 32° Baumé, 1-50 to 1-75. November 
or 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 parafiin-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° Baumé 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. 
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 
tor directions for making lime-sulphur solution see Farmers’ Bulletin 908. 
