142 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



RECORD OF EXPERIMENTS WITH SULPHUR DIOXIDE. 



Experiments 1 and 2 were conducted in the glass fumigating house 

 of the Bureau of Plant Industry. 



EXPEKIMENT NO, 1. 



Four per cent gas pumped into house for 10 minutes. Subjects of 

 experiment, various plants. Palms and pineapples were uninjured; 

 all the other plants were killed. 



In the course of this and the following experiment the escaping 

 gas blown by the winds over and more or less into adjoining green- 

 houses killed a great many delicate plants, doing much damage, the 

 tests showing conclusively the absolute impossibility of using this 

 gas for the fumigation of growing plants. Where also the gas flowed 

 for a few minutes over grass the latter was burned as though scorched 

 by fire, and killed to the ground. 



EXPERIMENT NO. 2. 



One hour treatment of several bushels of various kinds of seeds, 

 including Kafir corn, rice, rye, barley, and cowpeas. Beginning with 

 a strength of 6 per cent, the gas was increased to 12 per cent at the 

 end of half an hour, and to 16 per cent at the conclusion of the experi- 

 ment, the forcing of the gas into the building being continuous and 

 under pressure. The results of the germination tests of these seeds 

 by Mr. E. Brown, botanist in charge of the Seed Laboratory, indicated 

 that Kafir corn and rice were killed, the cowpeas were injured to the 

 amount of 10 per cent, and the rye and barley were substantially unin- 

 jured, 95 per cent germinating. 



Tests with insects were also made in jars very tightly plugged with 

 cotton. The Bruchus in cowpeas died in 40 to 15 minutes. All 

 free Calandras were killed; some still inclosed in the grain after- 

 wards emerged. In bags of grain all free insects were killed, but 

 some of the Calandras and Bruchus inclosed in grain and peas after- 

 wards emerged. 



Experiment No. 3.« 



Two hours at 10 per cent, machine running 5 minutes. Jars con- 

 taining insects were all tightly plugged with cotton, and none of the 

 insects were killed. 



Experiment No. 4. 



Treatment for 3 hours at 5 per cent, the machine running 5 min- 

 utes. (The lid of the box in the meantime had been made more 

 nearly air-tight by rubber packing.) 



a Experiments 3 to 12 were conducted at the Department insectary : Nos. 3 to 

 S in a small, zinc-lined fumigating box, and 9 to 12 in a building 10 by 10 by 10 

 feet, especially constructed for the purpose. 



