FUMIGATIOK. 333 



as possible, as to inhale the gas is fatal. After twenty- 

 five minutes, open the houses for at least half an hour, 

 but do not enter even then unless obliged to, except 

 with caution. At the usual price of pure cyanide of 

 potassium, 30 to 35 cents per pound, and of commercial 

 sulphuric acid, which can be bought in quantity at 

 three or four cents per pound, the cost of fumigating a 

 greenhouse will not be more than 12 to 15 cents per 

 1000 cubic feet. While it is very useful in destroying 

 aphides, it is a particularly valuable remedy against 

 insects and mealy bugs. 



One of the first uses to which it was put was the 

 destruction of white-tailed mealy bugs ( Orthezia insignis) 

 upon coleus, which had refused to yield to other reme- 

 dies. Its next extensive use was for the black violet 

 aphis, in the houses of Mr. W. G. Saltford, Poughkeepsie, 

 N. Y. (Fig. Ill), the results of which, as reported in 

 The Florist's Exchange, were very satisfactory. 



The same remedy is also much used upon nursery 

 stock that has been dug for shipment. An air-tight 

 shed arranged for ventilation is required. While in a 

 dormant condition the trees will stand a stronger gas 

 than will tender greenhouse plants. One ounce of the 

 cyanide of potassium and one and one-half ounces each 

 of water and sulphuric acid can be used with safety for 

 each one hundred and fifty cubic feet. For the San 

 Jose scale a second treatment will be desirable, but one 

 application will suffice for all other insects. The same 

 care about inhaling the fumes should be used here as in 

 a greenhouse. 



