586 



Journal of Agricultural Research 



Vol. XII, No. 9 



Table VI. — Toxicity of the vapor of certain organic compounds {in millionihs df a gram- 

 molecule required to kill in 15 hours' exposure). Compounds arranged from the m-ost 

 volatile to the least 



Fumigation in a saturated atmosphere with ether, ethyl mercaptan, 

 carbon bisulphid, benzene, carbon tetrachlorid, and chloroform will kill 

 all the eggs in one hour. 



SUMMARY 



(i) In general, compounds with high boiling point and slight volatility 

 are more eiffective in dipping and spraying insect eggs than compounds 

 with low boiling point and high volatility. 



(2) Compounds with low boiling points kill freshly laid eggs more 

 readily than eggs in which the embryo is partially or fully developed. 



(3) Compounds of higher boiling points are more toxic to eggs with 

 fully developed embryos than they are to eggs in which the embryo is 

 only slightly formed. 



(4) Kerosene containing both high and low boiling points is destruc- 

 tive to both young and old, but is only slightly toxic to partially devel- 

 oped eggs. 



(5) The toxicity of the vapor of organic compounds to insect eggs is 

 related to the boiling point and the volatility. As the boiling point 

 increases and the volatility decreases, the toxicity increases. 



LITERATURE CITED 



(1) COOLEY, R. A. 



1910. NOTES ON SPRAYING EXPERIMENTS FOR THE OYSTER SHELL SCALE IN 



MONTANA. In Jour. Econ. Ent., v. 3, no. i, p. 57-64. 



(2) Gillette, C. P. 



I910. SOME insecticide tests for the destruction op APHIDIDAE AND 



THEIR EGGS. In Jour. Econ. Ent., v. 3, no. 2, p. 207-210. 



(3) GoRTNER, R. A., and Banta, A. M. 



1914. notes ON the toxicity of dilute solutions of CERTAIN PHENOLIC 

 COMPOUNDS AS INDICATED BY THEIR EFFECT ON AMPHIBIAN EGGS AND 

 EMBRYOS, TOGETHER WITH REFERENCES ON MODIFICATIONS OP PIG- 

 MENT DEVELOPMENT. In Biochem. Bui., v. 3, no. 11/12, p. 357-368. 

 Literature cited, p. 368. 



