WELL TESTED INSECTICIDES 487 



22. HYDROCYANIC ACID GAS : 



Potassium cyanide 1 ounce 



Sulphuric acid 1 fluidounce 



Water 3 fluidounces 



or 



Sodium cyanide 1 ounce 



Sulphuric acid 1H fluidounces 



Water 2 fluidounces 



Place water and acid in earthenware vessel and add cyanide. To be 

 used under tents or tight rooms or boxes. 



For fumigating buildings or nursery stock, 1 ounce of cyanide to 

 each 100 cubic feet for 1 hour. 



For scale insects on citrus trees, maximum or Purple Scale dosage 

 found by mutiplying distance around by distance over top of tented 

 tree and pointing off two places. Example : 



Distance around Distance over 



40 feet X 20 feet = 8 ounces cyanide 



For Red or Black Scale, reduce one quarter. 



For details of fumigation processes for scale insects on citrus trees, 

 apply for publications to the University Experiment Station and td 

 Horticultural Commissioners in citrus fruit growing counties. 



