12 



m. Carbon bisulphid allowed to volatilize naturally is of littlo use. 

 At the rate of even 10 pounds per 1,000 cubic feet it will not kill wee- 

 vils buried beneath 4i feet or more of seed. At the rate of 4 pounds 

 per 1,000 cubic feet simply poured into a 100-pound sack it will not 

 always kill the weevils at the bottom. It is consequently useless in this 

 way for the fumigation of seed in large bulk. 



IV. When volatilized artificially, however, carbon bisulphid may be 

 used successfully in destroying the weevil in sacked cotton seed by 

 means of a comparatively cheap and simple apparatus. Every farmer 

 living in an uninfested region who obtains cotton seed from infested 

 parts should insist that it be fumigated in this way. The introduction of 

 the weevil into foreign countries could be prevented in the same way. 



CONTROLLING THE BOLL WEEVIL AT GINNERIES. 



On account of the great difficulty of destroying the boll weevils by 

 means of the fumigation of the bulk seed, which was demonstrated by 

 the foregoing experiments, the Department has concerned itself espe- 

 cially with an investigation to determine whether or not it is possible 

 to prevent the dissemination of the pest through the agency of gins. 

 The services of an especially trained gin expert, Mr. James Hull, who 

 has been actually engaged in the ginning business in Texas for four- 

 teen years, were obtained. He has made a careful study of all the 

 various systems of ginning cotton in this country, with special refer- 

 ence to the boll weevil. The suggestions offered in the following 

 pages are based upon his work. They have, moreover, been brought 

 to the attention of representatives of the principal ginning systems for 

 suggestions as to their practicability. Circulars have been addressed 

 to the 11,000 ginners in Texas and Louisiana in order to obtain an 

 exact knowledge of the various systems and combinations in use, in 

 order that the Department's suggestions may not be out of place in 

 view of the machinery that is in actual use. 



EXPERIMENTS TO DETERMINE EFFECTS OF MACHINERY ON 

 LIVE WEEVILS IN SEED COTTON. 



In addition to the foregoing basis for this report, a modern gin has 

 been run experimentally to determine several previously unsettled 

 points regarding the exact places in the system of ginning and han- 

 dling cotton through which the weevils may escape. The first of these 

 experiments was made to determine whether the weevils could pass 

 alive through the main fan in a pneumatic elevator system. Several 

 hundred live weevils, marked with colored pencils in such a manner as 

 to be easily recognizable, were fed into the suction tube between the 

 gins and the fan, after a large bag about 2^ feet in diameter and 16 



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