112 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 1 



and the stock fumigated for one half hour, one tree out of ten died. 

 In another case where the same quantities of chemicals were used 

 and the stock fumigated two hours, one-tenth of the trees failed to 

 grow. In all other cases of tests with this gas the trees lived and grew 

 nicely. The largest quantity used was three ounces of cyanide, and 

 the fumigation period was one-half hour. Two ounces for two hours 

 produced no injury. 



Sulphuretted Hydrogen. — Generated from iron sulphide, sulphuric 

 acid and water in the following proportions : 



Iron sulphide ...... 20 ounces 



Sulphuric acid ..... 80 ounces (fluid) 



Water 32 " 



In this proportion nine, twelve and one-half, and twenty-five pounds 

 of iron sulphide per one hundred cubic feet of space for one hour were 

 employed, the last quantity only causing injury to the trees. Where 

 this amount was used and the trees fumigated for two hours, only two 

 out of ten trees were killed. The scales were kiUed in all cases. 



This gas was rather inconvenient to use, as it takes a long time tO' 

 generate it. 



Chlorine. — Generated from bleaching powder, sulphuric acid and 

 water in the proportions given below: 



Bleaching powder ..... 14 ounces 

 Sulphuric acid ..... 17 ounces (fluid) 

 Water 70 '' 



The quantities used in these tests varied from 8.6 to 34.7 pounds per 

 one hundred cubic feet, and were probably all excessive. As we ex- 

 pected, all of the scales and most of the trees were killed. 



In reply to a question, Mr. Britton stated that he had not used 

 acetylene gas for fumigating fruit trees. Carbon tetrachloride ap- 

 peared worthy of further test. 



Mr. Hunter mentioned the fact that Mr. Sanborn had used acety- 

 lene gas to destroy plant lice on cucumber plants in Texas. 



Afternoon Session, Saturday, December 28, 1907 



On re-assembling at 1 p. m., three papers relative to the cotton boll 

 weevil work were presented, as follows : 



