258 



INSECTS INFESTING GRAIN. 



large scale is that, when stored, it is already infected. Fumiga- 

 tion alone will ensure that the seed is 

 entirely free from insects or insect eggs ; 

 fumigated seeds can be safely stored 

 but are not safe if improperly stored; 

 if seed is fumigated to-day, we know 

 we can store it as being free from 

 weevils, but if we leave it exposed 

 for another 



Fig. I. 



day, it may be infested 

 again. 



The best method of grain preserva- 

 tion is then to fumigate it and at once 

 store it in insect-proof bins or jars or 

 boxes, or in an insect-proof building. 

 A dry underground pit is suitable, if 

 properly insect-proof. Fumigation is a 

 process of exposing grain, seeds, etc., to 



Fig- 2 

 Scale 



F/ange 



<- Tin Lining 



Gutter 



the fumes of carbon bisulphide at a proper strength for a definite period ; 

 grain exposed to the fumes of carbon bisulphide at the rate of 1 oz. per 

 15 cubic feet of space for 24 hours will be free from all insects ; even the 

 eggs of the insects will be killed and the grain can be removed, the fumes 

 allowed to evaporate and the grain at once stored. Where large quantities 

 of grain are put into a 



godown till it is full and I Lid 



there is no extra air 

 space, we may use one 

 to one and a half Ibs. of 

 the fluid per ton of grain. 

 For fumigating jars or 

 small vessels, one tea- 

 spoonful (1 drachm) of 

 the fluid may be taken 

 for every cubic foot of 

 space. 



As carbon bisulphide 

 is an inflammable and un- 

 pleasant liquid to handle, 

 certain precautions must 

 be observed : 



(1) Keep the bisulphide in stoppered (not corked) bottles under lock 

 key, and in a place where it will not be liable to be thrown down, 



Side 

 of 



Box 



