FUMIGATION OF FRUIT TO DESTROY JAPANESE BEETLE 17 



area under quarantine for the beetle may be moved unless assurance 

 can be given that no infestation exists in them. The period during 

 which this ruling is in force is approximately July 1 to August 15, 

 the exact date being designated by the quarantine inspectors. 



DISCUSSION OF METHODS USED PRIOR TO 1930 



It had been hoped that the temperature produced in the cars as a 

 result of icing would kill all the beetles that might be present, but it 

 was found that they were merely rendered inactive. Attempts to 

 prevent infestation were made by screening the passage between the 

 fruit boat and the cars, but this method was unsuccessful. Since the 

 desired results were not obtained by physical methods, it was decided 

 to try chemical methods, and in this connection the use of a fumigant 

 seemed the most logical of all insecticidal measures. 



Although the usual way to obtain the answer to the problem would 

 have been to test the effect of a number of materials upon the beetle, 

 the need of a fumigant was urgent and it was decided to utilize the 

 results obtained from experiments conducted in the Bureau of Ento- 

 mology in 1926, 6 which indicated that hydrocyanic acid is very toxic 

 to the adult beetle. With this work as a basis the folloAving 

 recommendations were suggested : 



Three pounds of calcium cyanide (50 percent cyanogen (CN) 

 content) per refrigerator car, for 2 hours, the temperature inside 

 the car to be not less than 80° F. at the time of treatment. 



Tests were conducted with caged beetles in refrigerator cars under 

 the conditions recommended. As all the beetles were killed in these 

 tests, the tentative recommendations were adopted. Kesearch on 

 this problem was continued, however, and in view of subsequent 

 results the fumigation period was decreased to iy 2 hours. In candy- 

 ing out the fumigation 1 pound of the chemical was dropped into a 

 flat container in each ice compartment (fig. 13) and the remainder 

 was spread on the floor in the middle of the car. The hatches and 

 side doors were then closed for the required length of time, after 

 which the residues were removed and the doors sealed. The cars 

 were then iced, the covers of the ice compartments were fastened 

 open, and the openings were covered with screening to prevent re- 

 infestation. The car was not ventilated at the wharf, as ventilation 

 is accomplished by the passage of the air through the car during 

 transit by way of the screened openings of the ice compartment. 



This method was found to be very satisfactory in the case of 

 ventilated cargoes. Where refrigerated cargoes were concerned, 

 however, some injury was reported to have resulted from the treat- 

 ment. It was supposed that the dropping of the fumigant into the 

 bunkers caused the scattering of the smaller particles of the powder 

 and that these particles of the cyanide dust had reacted with the 

 moisture that had condensed on the surface of the cold fruit. This 

 injury was eliminated by spreading one-half of the required quan- 

 tity of calcium cyanide in each of two paper-lined wooden trays 

 (3 by 6 feet) outside the car, and then placing these on top of the 

 fruit (fig. 14). The trays were introduced at the start and removed 

 at the end of the fumigation period through the center doors in the 



Unpublished data of W. E. Fleming. 



