INSECTICIDES, PREVENTIVES, AND MACHINERY. 451 



The addition of pyrethrum extract to the kerosene emulsion 

 has been advised, but the increased effect has been small while 

 the cost is considerable ; hence the mixture is not now in use or 

 recommended. So the kerosene mixture of one quart of soft 

 soap, two quarts water, and one pint kerosene, where the water 

 is so hard as to make an emulsion impossible, has fallen into 

 practical disuse. 



Speaking broadly, the mineral oils are extremely useful insecti- 

 cides in most portions of our country, when their use is under- 

 stood and the applications are intelligently made; otherwise, they 

 are better left alone. 



Gasoline, a much lighter oil, is useful as a contact insecticide 

 in a limited number of cases. It can be applied to textiles 

 infested with "moths," or to carpets infested with "beetles." 

 It is very penetrating, kills everything it touches save eggs, and 

 evaporates rapidly without injury to the fabrics, or to the colors, 

 except of the poorest. It is also the best remedy for reaching 

 bed-bugs and other parasites that hide in crevices The material 

 is very inflammable, and must be used with that fact in mind at 

 all times. 



Turpentine is rarely used as an insecticide, but it is occasion- 

 ally added at the rate of one pint to a bushel of lime to keep off 

 the striped beetles from melon plants. 



Carbolic acid is valuable to a limited extent. It may be added 

 to the whale-oil soapsuds at the rate of one ounce of crude acid 

 to one gallon of suds, and this adds materially to its effectiveness, 

 especially as against the black plant-lice ; but as the same result 

 can be obtained by using less water in the soap mixture, it becomes 

 a mere question of expense and simplicity. 



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

 pint of the crude acid to every hundred pounds of the dry 

 hydrate increases its efficiency, and very few insects will touch a 

 surface so protected. The acid is mixed with the water used in 

 slaking the lime. 



As an emulsion it is prepared as follows : Dissolve one pound 

 of hard soap, shaved fine, in one gallon of boiling water ; add one 

 pint of crude carbolic acid, and churn with a force-pump until a 

 smooth, creamy emulsion is obtained. This remains stable for a 

 long time, and may be diluted with thirty parts of water for use 

 against root-maggots affecting cabbage, onions, and the like. It 



