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A TV ECONOMIC ENTOMOLOGY. 



allow it to cool. This makes an exceedingly caustic soap, which 

 is entirely reliable within its range of usefulness. 



Carbolic acid is also valuable as an insecticide, and can be used 

 in the form of an emulsion prepared as follows : one pound of 

 hard soap, shaved fine, dissolved in one gallon of boiling water, 

 into which one pint of crude carbolic acid is then poured, and 

 the whole mass made into an emulsion with a force-pump, used 

 as in the case of the kerosene. This emulsion remains more or 

 less stable for a long time, and can be diluted with thirty parts 

 of water for effective use against certain classes of insects. It has 

 been recommended for cabbage-maggots, and at the strength 

 given will not injure the plants, w^hile it seems to be fatal to the 

 young larvae. It is probably effective on soft-bodied insects in 

 general, but it undoubtedly derives a considerable proportion of 

 its effect from the presence of the large quantity of soap in the 

 emulsion. 



Where lime is to be used as a repellent, the addition of one 

 pint of crude carbolic acid to one hundred pounds of the dry 

 hydrate wall increase its efficiency, and few insects will touch 

 plants so protected. Among these few insects, however, we 

 find the rose-chafer. 



The addition of carbolic acid to the whale-oil soap mixture is also 

 advantageous in certain cases. One ounce of crude carbolic acid 

 in each gallon of whale-oil soap mixture increases its effectiveness 

 as against plant-lice very considerably. One pound of whale-oil 

 soap in eight gallons of water, with four ounces of carbolic acid 

 added, will double the effectiveness of the mixture ; but as the 

 same result can be obtained with the soap alone in four gallons 

 of water, it becomes a mere question of cost and simplicity. 



The whale-oil soap is often used in the form of a wash to pre- 

 vent the entrance of borers into fruit-trees, and in such cases the 

 addition of an ounce of the acid in a gallon of soapsuds seems to 

 add to its efficiency. It is claimed that trees treated with such 

 a mixture are much less attacked than those treated with the 

 soap alone. A little lime is sometimes added to a liquid of this 

 kind to make it more permanent. 



Lime alone is useful as an insecticide in some instances. It 

 has been found effective by some and absolutely useless by 

 others, the difference in result being often due to a difference 



