226 INSECTS AFFECTING VEGETATION 



definite information on this subject. It should be known that there 

 is no variety of grain that is weevil proof. However, the condition in 

 which the grain is kept is of some importance. In general, unhusked 

 grain is much freer from attack than grain that has been husked. 

 Corn is much more subject to attack when shelled than when left on 

 the cob. Those varieties of corn that have hard, flinty kernels and 

 close fitting husks are not so subject to attack as other varieties. But 

 it is hardly profitable to discuss these various preventive measures as 

 we have in carbon bi-sulphide, a remedy that is effective, cheap, and 

 simple in its application. Its use is yearly becoming much more gen- 

 eral. Carbon bi-sulphide is a chemical compound of the formula 

 C. S 2 ; as the name and symbol indicate, it is bisulphide of carbon. It 

 is a colorless liquid, having a very strong, disagreeable odor, and is 

 quite volatile, vaporizing at an ordinary temperature. It is also 

 highly inflamable, and hence in its use care should always be taken 

 that no fire of any kind be brought near it. A lighted match, lighted 

 pipe or lighted cigar should not, under any circumstances, be brought 

 near a building that is being fumigated. The fumes of this com- 

 pound are very poisonous. Therein lies its value as a destructive 

 agent against insects. The deadly fumes of this compound enters 

 their breathing tubes with the air which they breathe and quickly 

 brings about their death. The fumes are also poisonous to other 

 animals, but there is little danger to man from inhaling a small 

 quantity. 



The application of carbon bi-sulphide is but a process of fumi- 

 gation, and in order that the fumes may be kept within the bin or 

 crib they should be as tight as possible. If they are not tight much 

 more of the compound will be required. Bins may be made much 

 tighter by covering them as much as possible with cloths and blank- 

 ets. Oil cloth and heavy canvas are excellent. In a moderately 

 tight bin one pound of the sulphide should effectually fumigate one 

 hundred bushels of grain. Several methods are in use for the appli- 

 cation of the sulphide. A ball of cotton tied to a stick may be satu- 

 rated with the compound and pushed down to near the center of the 

 grain. By doing this, it is believed that the air becomes more evenly 

 saturated with the sulphide. Another method consists in pushing a 

 long pipe, in which is a tight fitting rod, down into the grain. The 

 rod is withdrawn and the carbon bi-sulphide poured into the tube. 

 But the most effective way of applying the compound, when the bins 

 are moderately tight, is to pour the reagent in shallow dishes or pans 

 which may be placed here and there on the top of the grain. The 

 compound being volatile rapidly vaporizes, and being heavier than 

 air, sinks and becomes thoroughly diffused throughout the bin. Balls 

 of cotton or waste may be saturated with the sulphide and distributed 

 over the surface of the grain. In case all the insects are not destroyed 

 by one application, another should be made. Grain treated with the 

 sulphide is not injured for food purposes, or for seed. To secure the 

 very best results from the use of carbon bi-sulphide a tight quaran- 

 tine bin should be made, somewhat separated from the other build- 

 ings, where the grain may be subjected to a thorough fumigation be- 



