2 CIRCULAR 3 7 3, U. S. DEPARTMENT OF AGRICULTURE 



quarantined area. This was unsatisfactory because the fruit was in- 

 jured by excessive handling, the inspection was slow and laborious, 

 and there was the possibility of failure to discover all the beetles. 

 It was therefore necessary to develop a practical method for elim- 

 inating the danger of transporting Japanese beetles with the fruit, 

 The Japanese beetle is often found resting or feeding on the fruit 

 or the foliage of plants in the season when the crop is harvested, 

 and it is impossible to pick the fruit at a time of day when beetles 

 are not present. As the ordinary contact sprays and stomach poi- 

 sons are ineffective for eliminating infestation in berry fields, some 

 physical or chemical method had to be developed for destroying 

 the beetles in the crates and boxes. Fumigation seemed to be the 

 most practical procedure. 



PRELIMINARY EXPERIMENTS 



Preliminary tests were made in the summer of 1928 with carbon 

 disulphide, benzene, ethyl acetate, trichloroethylene, ethylene di- 

 chloride, decahydronaphthalene, ethyl bromide, and geraniol. These 

 materials were tested at different temperatures, both at room pres- 

 sure and under partial vacuum, to determine their effectiveness in 

 killing beetles and the effects of fumigation on the berries. 



The results of these preliminary tests indicated that carbon di- 

 sulphide at room pressure, used at the rate of 10 pounds to 1,000 

 cubic feet, was effective in destroying beetles when the treatment 

 was prolonged for 2 hours at a temperature of 80° F., and that 

 such treatment would not be detrimental to the fruit. 



PROPERTIES OF CARBON DISULPHIDE 



Carbon disulphide is a liquid with a specific gravity of 1.29 at 

 the freezing temperature of water and with a boiling point of 

 46.2° C. (114.2° F.). It should be kept in an outhouse away from 

 lights and fires. It is very volatile, evaporating rapidly when ex- 

 posed to air. The vapor is highly inflammable ; when mixed with 

 air in the proper proportions it is explosive; and at 147° C. (296.6° 

 F.) it ignites spontaneously. Pure carbon disulphide, according 

 to Hinds (4) 5 4 is completely volatile, and does not impair the edi- 

 bility of foodstuffs, even when poured directly upon them. All 

 trace of the odor disappears quickly when the compound is exposed 

 to air. The ordinary article, however, has a slightly yellowish 

 tinge caused by its impurities, which also give it a rank, fetid, ob- 

 noxious odor. When the impure article is used, a slight residue 

 may be left after the evaporation of the liquid. 



The vapor of carbon disulphide, because of its density, will work 

 downward. This point has an important bearing upon the applica- 

 tion of the material as a fumigant. For the best results, means 

 should be employed to give an even distribution of the gas. 



THE FUMIGATION HOUSE USED FOR THE TESTS 



The effectiveness of carbon disulphide as a commercial fumigant 

 was determined in a fumigation house of 1,000 cubic feet capacity, 



i Italic numbers in parentheses refer to Literature Cited, p. 28. 



