96 INSECTS AFFECTING THE ORANGE. 



Wluile-oil soap is sold in Eastern Florida at 10 to 12 cents per pound. 

 The cost of an efi'ective wash is therefore much greater than emulsions 

 of kerosene. For scrubbing and cleansing the trunks of orange trees 

 this soap may be recommended. A solution of 1 pound to 4 gallons 

 will probably be sufficiently strong for this purpose. 



Potash and Soda Lye. — These substances have been recommended as 

 remedies for Scale-insect iu California. According to rei)orts promul- 

 gated by the State Horticultural Commission, solutions as strong as 1^ 

 pounds to the gallon of water are deemed necessary to exterminate the 

 pest, and are said to have been used with good results upon Peach, 

 Pear, and other deciduous fruit-trees. Although these caustic solu- 

 tions burn and partially destroy the bark, it is said to be soon restored, 

 and no lovss of fruit results if applied in winter while the trees are dor- 

 mant. 



Experiments made in Florida upon the Orange with caustic soda and 

 potash lyes show that solutions of 1 pound to 2, 2h, and 3 gallons 

 were of little or no practical benefit as regards the extermination of 

 Scale-insects, while the effect upon the trees was more severe than with 

 applications of pure kerosene. Cnlike kerosene, lye is injurious to the 

 tender portions of the plant, and new growth is destroyed at once by 

 strong solutions. Solutions of 1 pound to the gallon severely cauterize 

 the leaves and tender bark, and kill back the smaller braoches, but fail 

 to destroy all the Bark-lice, and have bardlj' an appreciable effect upon 

 their eggs. (See Appendix II, table o.) 



Concentrated potash is somewhat stronger than soda lye, but the re 

 suits attained with it are also unsatisfactory. In the strongest appli 

 cations, made with a solution of two pounds of potash to one gallon of 

 water, the trees were burned as by fire, the leaves were charred with- 

 out falling from the branches, all the growth under two years old was 

 destroyed, and the main trunks alone remained alive. The S(;ale-insects 

 perished with the cauterized bark and foliage ; nevertheless, a very 

 large percentage of their eggs escaped destruction, and continued to 

 hatch. A few days later the young were seen in abundance, crawling 

 over the blackened trunk and branches. It is probable that they all 

 ])erished, however, through inability to i)enetrate the cicatrized bark 

 with their sucking beaks. The trees thus treated surviveil, indeed, but 

 in a mutilated condition and with an entire loss of symmetry in their 

 tops. 



It would ai)pear from careful experiments and observations with both 

 s(Mla and j)otash lyes, that these substances are inferior to kerosene in 

 killing power as regards Scale-insects, and far more injurious to the 

 tree when used in solutions strong enough to be effective as insecti- 

 cides. Weaker solutions are, however, extremely useful in cleansing 

 the trunks of orange trees with the scrubbing brush. For this [)urpose 

 they are superior to solutions of soap, and have an advantage over di- 



