454 HOUSEHOLD INSECTS 



Unfortunately, the vapor does not penetrate dry cereals, 

 like flour, bran, and meal, as thoroughly as it ought, to 

 give wholly satisfactory results. Smith found that 

 three pounds of carbon bisulfide to one thousand cubic 

 feet in a practically air-tight room for twenty-one 

 hours did not kill over 70 per cent of the larva? and 

 pupa? of the Angoumois grain moth or rice weevil. It 

 did, however, kill practically all of the adults. 



Again, the effect of the vapor on flour has been care- 

 fully noted by Harcourt. He fumigated a sample of 

 flour with carbon bisulfide for twenty-four hours. From 

 this sample he made three different bakings, varying 

 from two to two and one-half months apart. In each 

 case the flour treated with the carbon bisulfide did not 

 produce as good bread as the untreated, normal wheat 

 flour. "The loaves were smaller, darker in color and 

 poorer in texture and in general appearance." However, 

 the third baking was the best and showed that the flour 

 was recovering from the effects of the vapor. Probably 

 all effects of the vapor would have disappeared in time. 



It is generally said that even when the carbon bisulfide 

 is poured directly upon food-stuffs their edibility is not 

 impaired. All trace of the odor disappears in a short 

 time after exposure to the air. Undoubtedly, this is 

 generally true and most food-stuffs are not injured. De- 

 spite the objections already noted to the use of carbon 

 bisulfide, it still remains one of our most useful insec- 

 ticides for certain insects. 



Directions for its use. In the first place, the room 

 which is to be fumigated must be as near air-tight as 

 possible. If it is full of openings and cracks, satisfac- 

 tory results must not be expected. Whenever practi- 



