CHAP. XI. j THE CONTROL OF INSEC1 PESTS OF CROPS. 103 



Various forms of crude carbolic and en monly sold 



for use as disinfectants are also useful as contact insecticides when 

 used as a strength of about one in eighty of water. 



Tobacco Decoctions give excellent killing results against soft- 

 bodied insects without harming foliage. One pound of Tobacco 

 leaves or stems is steeped in four gallons of hot water and the 

 mixture applied directly when cool. If soap is added, at the rate of 

 one pound to twenty gallons, the mixture is made much n 

 efficient. Tobacco stems and dusl applied at the roots of bushes 

 ami to the surface of the soil aroui bles will often drive 



away and destroj grubs, worms and small pests. 



Sulphur, in the finely-divided form known as Flowers of Sulphur 

 is valuable against Mites of all sorts. It may be used dry, being 

 dusted onto the plants by itself or mixed with lime, flour or road- 

 dust, or may be sprayed on at the rate of one pound in two to four 

 gallons of water. As the inseetieidal action of sulphur is due to its 

 oxidation under the influence of warm sunlight, it must be applied 

 in the early morning. 



Lime-Sulphur, a chemical combination of lime and sulphur and 

 which kills insects by its caustic properties, has lately come into 

 extensive use in America as a spraj for use on dormant trees in the 

 winter-time. It has not been used in India but may perhaps be 

 found useful .it considerable dilution. It may be prepared by heat- 

 ing three gallons of water in a barrel or vessel, which must not be 

 made of copper, and adding four pounds of unslaked lime and 

 immediately adding three pounds of flowers of sulphur previously 

 made into a thick paste with water. After the lime has all slaked 

 another three gallons of hot water is added and the heating 

 continued for an hour after which another four gallons of water is 

 added and the whole thoroughly stirred and strained. At this 

 strength the mixture- will burn foliage and requires five or six times 

 dilution before use; it may be used undiluted for painting bob 

 trees to prevent the attacks of porcupines, rats. etc. 



Self-boiled Linn-Sulphur may also be prepared and used as a 

 spray for foliage and is especially useful, if lead arsenate be 

 added, as a combined insecticide and fungicide'. To make it, 

 twenty pounds of quicklime are placed in a barrel or other suitable 

 receptacle — copper vessels must not be used and three gallons ,,i 

 cold waterare poured over it; as soon as the slaking is well started, 

 sift in twenty pounds of flowers of sulphur, and stir the mixture 

 well. The violent heat generated by the- slaking of the lime will 

 bring about .1 chemical combination between the- lime and the 

 sulphur. Mme cold watei is added until the n paste-like 



