16 BULLETIN 363, U. S. DEPAETMEXT OF AGEICULTUEE. 



The additional handling mcident to the husking process is also of 

 benefit, as many of the larvae are dislodged thereby, and the husked 

 ears afford httle concealment for pupation and for the feeding of 

 the larv83. 



The best ears when dry could be saved to a considerable extent 

 by placing them in an isolated weevil-and-mouse-proof fumigator 

 such as a metal crib, to be made as nearly air-tight as possible. 



CARBON BISULPHID. 



In the South, where the pink corn-worm is so injurious, bisulphid 

 of carbon is the best remedy and has already been used for its control. 

 Carbon bisulphid, or bisulphid of carbon (CSj), is a heavy liquid, 

 colorless when pure, and is one of the standard chemicals for the 

 control of insects injurious to stored products. Its value lies in the 

 fact that it is extremely volatile, passing into the open air as a heavy 

 gas which settles to the bottom of receptacles in which the liquid is 

 exposed and, by replacing the air, causes suffocation. It is much 

 used against the Angoumois grain moth and various other insects 

 injurious to corn and other cereals. It is less poisonous to human 

 beings than hydrocyanic-acid gas and, while there is danger from 

 fire owing to its inflammability, with a reasonable amount of care 

 this chemical may be cheaply and effectively applied to almost any 

 stored product infested by insects. 



It is more effective at a high temperature, 76° to 90° F. proving 

 the best for its use. It is less effective under 70°, and not efficient as 

 low as 50° F. 



DIRECTIONS FOR USE. 



Since carbon bisulphid is extremely volatile, it is best evaporated 

 in flat vessels — milk pans, pie tins, and cheap plates serving this 

 purpose admirably. An average application is 2 or 3 pounds to 1,000 

 cubic feet of air space, or 1 pound to 100 bushels. Less may be used, 

 but it has been found that in a structure which can not be made 

 positively air-tight it is necessary to use this amount to insure 

 success. The liquid is poured into the evaporators, a half pint or 

 more in each, and, as the gas is heavier than air, the evaporators are 

 then placed in the higher parts of the bin or fumigator. Evaporating 

 pans are frequently set on the top of the grain, allowing the gas to 

 penetrate to the bottom, or, in the case of shelled corn, a perforated 

 tube, such as a drive-well point, may be thrust into the grain and the 

 requisite amount of the liquid poured therein. 



When the gas is used in open bins or other receptacles the surface 

 of the grain should be covered with heavy tarpaulin or canvas. The 

 bin should be kept closed as tightly as possible for about 36 hours; 

 this will not destroy the germinating power of the seed. With grains 

 not desired for planting the bins may be allowed to remain closed as 

 long as the gas evaporates. 



