BEMED1ES AGAINST SCALE-INSECTS. 97 



lute kerosene emulsions, in that they destroy the spores of lichens and 

 fungi, which kerosene does not. 



Crude Carbolic Acid or Oil of Creosote. The crude oil, dissolved in 

 strong alkalies or solutions of soap, forms a very effective remedy for 

 Scale-insect. It may also be emulsified with milk in the same manner 

 as kerosene. The undiluted oil is, however, exceedingly injurious to 

 vegetation, and destroys the bark of Orange and other trees. It is, in 

 fact, a more dangerous substance than kerosene, and requires to be used 

 with great caution. Solutions, emulsions, and soaps containing it should 

 be very carefully mixed, in order that no globules of free oil may be 

 allowed to come in contact with the bark of the tree. 



Its action upon the Scale-insect is even more powerful than kerosene, 

 but it does not destroy as large a percentage of the eggs. The effect 

 upon the Coccids is not immediate, as in the case of other insecticides, 

 and for three or four days after an application very few of the insects 

 die. At the end of a week, however, the Bark-lice are found to be 

 affected and continue to perish in increasing numbers for a week longer. 

 Even after the lapse of three weeks the destructive action of the oil is 

 still appreciable. These facts lead one to suspect that the insects are 

 killed, in part at least, by the poisoning of the sap upon which they feed. 



The visible effect upon the plant appears to confirm this view. Leaves 

 upon infested trees begin to drop after four or five days, and the defolia- 

 tion reaches a maximum during the second week. As is the case with 

 kerosene, the effect upon the tree depends upon its condition at the 

 time of application ; but carbolic acid is more severe in its action, and 

 there is greater loss of leaves and infested branches. With care, how- 

 ever, an application may be made sufficiently strong to exterminate the 

 scale without serious injury to the plant, and, as new or vigorous growth 

 is very slightly affected, recovery is rapid. 



The following solution of crude carbolic acid will be found nearly if 

 not quite as effective as a G4 per cent, kerosene emulsion, and may be 

 applied without danger to orange trees. Dilute the carbolic acid with 

 twice its volume of soap solution (2 ounces common soap to I pint hot 

 water). Mix thoroughly until all the oil is dissolved. Add, before 

 using, to one part of the above solution twenty parts water, and apply 

 in as fine spray as possible. 



The most effective method of using oil of creosote is to saponify it 

 with heavy oils and potash. In this way a solid soap containing about 

 12 per cent., by volume, of the oil may be obtained. The process of 

 making the soap is, however, exceedingly tedious and difficult, and un- 

 less proper appliances be used the resulting product is imperfect and 

 even dangerous to use, as it contains a large amount of free creosote. 

 Manufacturers of carbolic soap could undoubtedly supply a better article 

 and at a less cost than the consumer could make for himself. 



(For detailed experiments see Appendix II, Table 4.) 

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