38 



BULLETIN 1313, U. S. DEPARTMENT OF AGRICULTURE 



With the exception of four cars fumigated for milling and baking 

 tests, the rice weevil (S. oryza) was the test insect used in the pill boxes. 

 Furthermore, the grain in all but two of the cars was moderately 

 infested with weevils. The results given in the last column in 

 Table 1 4 show the percentage kill of this natural infestation. 



The results of the car fumigation reported in Table 14 confirm those 

 reported in Table 8. 



With the exception of one case, where fumigation was inter- 

 rupted, all fumigations with a mixture of 40 per cent by volume of ethyl 

 acetate and 60 per cent by volume of carbon tetrachloride, in which 

 not less than 40 pounds of the mixture per 1,000 cubic feet of inclosed 

 space was used, gave satisfactory kills. 



The results of the milling tests with the wheat fumigated in these 

 box-car experiments are shown in Table 15; the results of the baking 

 tests with flour made from this wheat are shown in Table 16. The 

 data indicate that both the flavor and odor of bread baked from flour 

 made from wheat fumigated in box cars with a mixture of 40 volumes 

 of ethyl acetate and 60 volumes of carbon tetrachloride, at the rate of 

 40 pounds per 1,000 cubic feet, are normal. 



EFFECT OF ETHYL ACETATE-CARBON TETRACHLORIDE 

 FUMIGATION ON GERMINATION OF SEEDS 



The seeds of wheat, barley, rye, winter oats, and corn in tightly 

 closed bell jars were exposed to the vapor of ethyl acetate and carbon 

 tetrachloride at a concentration of 40 pounds per 1,000 cubic feet 

 for 24 hours. The percentage germination before and after fumiga- 

 tion is shown in Table 17. 



Table 



17. — Effect of et 



hyl acetate-carbon tetrachloride fumigation 

 of seeds 



on germination 











Seed 



Germination 



Seed 



Germination 





Before 



fumiga- 

 tion 



After 

 fumiga- 

 tion 



Before 

 fumiga- 

 tion 



After 

 fumiga- 

 tion 



Wheat. 



Per cent 

 83 

 97 

 89 



Per cent 

 85 

 98 

 90 





Per cent 

 95 

 97 



Per cent 

 93 







94 



Rye 











The results in Table 17 show that exposure at 31° C. in a tight 

 container for 24 hours to the fumes of a 40-60 mixture (by volume) 

 of ethyl acetate and carbon tetrachloride at the rate of 40 pounds 

 per 1,000 cubic feet does not injure the germinating power of wheat, 

 barley, rye, winter oats, and corn. The grain would not be subjected 

 to as severe a test in ordinary box cars. 



SUMMARY 



The action of more than 100 organic compounds on weevils was 

 tested under conditions permitting a control of the factors of con- 

 centration, time, and humidity, and with observations of the tem- 

 perature. 



The following 30 compounds were more toxic to the rice weevil 

 (S. oryza L.) than carbon disulphide: Two out of 8 bromides tested; 



