INSECTICIDES. 



used as a spray against aphids and other soft-bodied 

 insects. House-plants may be dipped in this solution 

 after it has cooled. 



Among the repellants, tobacco dust, air-slacked lime, 

 soot, and even fine road-dust may be mentioned but they 

 are effective only so long as the plants are covered with 

 them. "Fruit trees are often painted with a thick soap 

 solution containing I pint of crude carbolic acid to 10 

 gallons as a repellant for the adult borers which lay their 

 eggs on the bark." Tanglefoot is a sticky paste such as is 

 used on fly-paper and, if a tree-trunk be encircled with it, 

 crawling insects, such as caterpillars, will be kept from 

 getting up. Do not be taken in by the charlatans who 

 bore holes in trees and then plug them with something or 

 other, on the theory that the sap will take up the poison and 

 carry it to the leaves. 



The principal insecticidal gases are carbon bisulphide, 

 hydrocyanic acid, and the fumes of burning tobacco and 

 sulphur. CarbcJh bisulphide is bad smelling, and will cause 

 a headache if inhaled, and is very explosive but, if used 

 with caution, is good for fumigating closets, entomological 

 collections, and against boring and root-feeding pests, also 

 to put in ants' nests. In buildings ' ' there should be I square 

 foot of evaporating surface to every 25 square feet of floor 

 area, and each square foot of evaporating surface should 

 receive from one-half to i pound of liquid." Hydrocyanic 

 acid gas is so poisonous that I will not risk giving directions. 

 If you want them, write to your State entomologist or to 

 the U. S. Department of Agriculture. If sulphur be burned 

 at the rate of two pounds per thousand cubic feet of space 

 it is said to be effective against bedbugs and the like, but it 

 will not kill the eggs, whereas kerosene will. Furthermore, 

 it bleaches fabrics, if they be at all moist, and kills plants, 

 if it be too strong. Tobacco fumes are safe ad lib. 



Farmer's Bulletin, 127 of the U. S. Department of 

 Agriculture tells a great deal about insecticides. This 

 same Department will send you, free, a monthly bulletin 

 which gives a list of their publications. Many of the 

 publications have interesting accounts of insect life- 

 histories and are worth having, even if the economic 

 phase of the question does not appeal to you. 



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