20 



CIECULAE 3 7 3, IT. S. DEPARTMENT OF AGRICULTURE 



fumigating house), a temperature of 80° F., and an exposure of 

 2 hours. Under these conditions a complete larval mortality was 

 obtained with 3 ounces of compound no. 1, and with 1 ounce of com- 

 pound no. 2 or no. 5. 



Tests with compounds nos. 3 and 4 could not be run as indicated 

 above because these materials are ordinarily unobtainable in pack- 

 ages smaller than 



100 -n ^ mn-n nmn smtn — i ljiiilu 1 pound, although 



for experim ental 

 purposes " 4 - ounce 

 cans " were supplied 

 by the manufactur- 

 ers. As indicated be- 



80 



60 



o 



K 

 UJ 



O^ 



<r 

 o 



20 



cans " meant a net 

 weight of 4 ounces 

 of hydrocyanic acid, 

 and it is obvious 

 that the contents of 

 these cans could 

 not be divided into 

 1-ounce portions 

 with any degree of 

 accuracy. Conse- 

 quently, an experi- 

 ment was run with 4 

 ounces of each of 

 compounds nos. 1 

 to 4 7 to determine 

 the relative toxicit}^ 

 by the length o f 

 time required for 

 each to effect a com- 

 plete kill. The experiment was repeated, 1 pound instead of 4 ounces 

 of each compound being used. The results of these experiments are 

 shown in table 3 and graphically in figures 15 and 16. 



Table 3. — Mortality of Japanese beetle larvae from different periods of exposure 

 to 4 ounces and 16 ounces of fumigating material per 1,000 cubic feet at 

 80° F. 



90 



15 30 45 60 



TIME OF FUMIGATION (MINUTES) 



C0MP0UNd{|[] 2§ 3[JJ 4g] 



Fioure 15. — Mortality of Japanese beetle larvae after expo- 

 sure to compounds nos. 1 to 4 (4 ounces per 1,000 cubic 

 feet) at 80° F. 





Time of 

 fumigation 



Mortality of larvae 



Quantity of material (ounces) 



Compound 

 no. 1 



Compound 

 no. 2 



Compound 

 no. 3 



Compound 

 no. 4 



4 1— -12— 



Minutes 

 15 

 30 

 45 

 60 

 90 

 15 

 30 

 45 



Percent 

 13 

 23 

 56 

 85 



100 

 33 

 95 



100 



Percent 

 10 

 78 

 94 

 99 



100 

 17 

 95 



100 



Percent 

 96 

 100 

 100 

 100 

 100 

 100 

 100 

 100 



Percent 



99 



4 



100 



4 - - - - 



100 



4 



100 



4 _'. 



100 



16 



16 



100 

 100 



16 



100 



7 No furtber tests were run with sodium cyanide (compound no. 5), as in refrigerator 

 cars the use of this material with the necessary cumbersome equipment seemed 

 impractical. 



