ARTIFICIAL DISSEMINATION. 91 



There is another method of natural spread of some local importance. 

 In hill lands, especially, rains sweep immense numbers of infested 

 squares to the lower parts of the fields. Cotton squares are remark- 

 ably impervious to water, and weevils may develop in them after 

 decay is far advanced. These squares may be carried many miles 

 from their source and deposited under favorable conditions for the 

 emergence of the weevils. 



ARTIFICIAL DISSEMINATION. 



While the natural dispersion of the boll weevil is by far the most 

 important means by which new territory becomes invaded, there are 

 certain artificial means of dissemination which are of some importance. 

 The more noteworthy of these are connected with the handling of the 

 cottonseed and cottonseed products. Many weevils are carried to 

 the gins with the cotton. From the gins dissemination may take 

 place in several ways. The weevils may be carried back to the farms 

 in cottonseed to be used for planting, or they may be shipped by rail 

 to the oil mills along with the seed. Moreover, weevils are likely to 

 secrete themselves during cool weather in the wrapping of cotton bales. 

 In this manner transportation along with the lint is possible, although 

 experience has shown that the danger from this source is inconsid- 

 erable. When the cottonseed arrives at the oil mill there is chance 

 of infestation from flight into neighboring cotton fields. The greater 

 damage, however, is in the shipment of weevils beyond the oil mills 

 in the cars which have been used for the purpose of carrying the seed 

 to those establishments. 



Among the means of minor importance may be mentioned the inci- 

 dental carriage by vehicles, including railroad coaches, by the move- 

 ment of plantation laborers, and by intentional carriage for the 

 purpose of experimentation or exhibition. The possibility of spread 

 by these various means will be discussed in the following paragraphs: 



MOVEMENT OF SEED COTTON. 



Many immature or teneral weevils are carried to the gins with the 

 seed cotton. Adults are frequently found crawling over the wagons 

 filled with unginned cotton. The devices for removing foreign matter 

 from cotton in the process of ginning are numerous and effective. 

 Many of the weevils are removed or destroyed, but adults, as well as 

 larvae and pupse, are likely to pass through the gin with the seed. 

 This has been determined by the Bureau of Entomology by running 

 gins experimentally. 1 Many of the weevils, consequently, are carried 

 into the seedhouse along with the cottonseed. Moreover, many of 

 those that are removed by the cleaning devices are not injured. They 

 pass along with the motes into a barrel or box, which is generally 

 uncovered, and from there they frequently fly about and find their 

 way into the cottonseed, or they may secrete themselves in the 

 bagging of the bales standing in the gin yard. Furthermore, many of 

 the adult weevils are not taken into the gin house at all. Being on 

 the cotton in the wagon, they are disturbed by the process of unload- 

 ing and may fly to any portion of the plant. Consequently, cotton- 

 seed in storage at the gin may become infested by any one of the 



1 For a full account of these experiments see Farmers' Bulletin 209. 



