INSECTS INJURIOUS TO STORED GRAINS 197 



known of old, and a building in which any artificial heat is 

 employed is undesirable for grain storage. The ' heating ' and fer- 

 mentation of grain, as is well known, is productive of ' weevil,' and 

 this should be prevented by avoiding moisture and by ventilation- 

 " The storage of grain in large bulk is to be commended, as the 

 surface layers only are exposed to infestation. This practice is 

 particularly valuable against the moths, which do not penetrate 

 far beneath the surface. Frequent agitation of the grain is also 

 destructive to the moths, as they are unable to extricate them- 

 selves from a large mass, and perish in the attempt. The true 

 granary-weevils (small dark-brown beetles with long curved 

 snouts, similar to the pea- weevil), however, penetrate . more 

 deeply, and although bulking is of value against them, it is not 

 advisable to stir the grain, as it merely distributes them more 

 thoroughly through the mass." Chittenden. 



Destruction of " Weevil " 



Carbon Bisulfide. " The simplest, most effective, and most 

 inexpensive remedy for all insects that affect stored grain and 

 other stored products is the bisulfide of carbon, a colorless liquid, 

 with a strong disagreeable odor, which, however, soon passes 

 away." At ordinary temperatures it vaporizes rapidly, forming a 

 heavy gas, which is highly inflammable and a powerful poison. 



Application. It may be applied directly to the infested grain 

 or seed without injury to its edibleness or viability by spraying 

 with an ordinary watering-can having a fine rose nozzle. In 

 moderately tight bins it is more effective, however, as it evaporates 

 more slowly and diffuses more evenly, if placed in shallow dishes 

 or pans, or on bits of cloth or cotton waste distributed about on 

 the surface of the grain or infested material. The liquid volatil- 

 izes rapidly, and, being heavier than air, descends and permeates 

 the mass of grain, killing all insects and other vermin present. 

 The bin should then be covered with 1 wards, canvas, or blankets, 

 and allowed to remain at least twenty-four hours. If to be used 

 for seed, it should not be left for over thirty-six hours; but if not, 



