258 



INSECTS INFESTING GEATN. 



Fig. I. 



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 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 



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 



there is no extra air 



space, we may use one 



to one and a half lbs. 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 



and key, and in a place where it will uot be liable to be thrown down, 



Lid 



Fig. 2 



SoalQ \ 



Flange 

 ^^ Tin Lining 



