380 MANUAL OF VEGETABLE-GARDEN INSECTS 



In generating the gas, the pr()per procedure is to place the 

 water in an earthen jar of suitable size. Butter crocks are 

 convenient for this purpose. The acid is then added to the 

 water, generating considerable heat. The water should never 

 be poured into the acid, since the steam produced will cause a 

 vigorous bubbling and the acid may be spattered on the operator. 

 After the acid has mixed with the water, the proper quantity 

 of cyanid is placed in the liquid. The rapidity with which the 

 gas is generated will depend on the temperature of the liquid 

 and on the size of the lumps of cyanid. 



For destroying white-fly on tomatoes and cucumbers grown 

 under glass, potassium cyanid should be used at the rate of 1 

 ounce (or sodium cyanid, f ounce) to 3000 cubic feet of space 

 contained in the house and the fumigation should continue 

 all night. Fumigate only on dark dry nights when there is no 

 wind. The house should be as dry as practicable and the 

 temperature not above 60 degrees F. 



Carbon bisulfid is often used for fumigating peas and beans 

 infested with weevils and potatoes infested with the tuber- 

 moth. Carbon bisulfid (CSg) is a thin liquid that volatilizes 

 at a low temperature, the vapor being very destructive to 

 animal life. It is very inflammable and care should be taken 

 not to bring it in contact with fire or with a lighted lamp. 

 One should not smoke w^hile fumigating.- In fumigating peas 

 and beans infested with weevils the seed should be placed in a 

 tight box or barrel to which a cover has been fitted as nearly 

 air-tight as possible. Carbon bisulfid is used at the rate of ^ 

 t.) 1 ounce a bushel. In larger quantities in specially con- 

 structed fumigating chambers, the weevils can be killed by 

 using the liquid at the rate of 3 pounds to 1000 cubic feet. The 

 material is placed in a shallow dish on the top of the seed. The 

 box should then be covered tightly and the fumigation con- 

 tinued for twenty-four to thirty-six hours. 



In fumigating potatoes to destroy the tuber-moth, the 



