Januaet 28, 1910] 



SCIENCE 



151 



perhaps unfortunate but not essential to decide 

 the question at issue. 



Affirmative, 13; negative, 0; not voting, 2. 

 C. W. Stiles, 

 Secretary of Commission 



TEE MEXICAN COTTON BOLL WEEVIL 

 Probably the control of no insect pest has 

 involved greater difficulties than that of the 

 cotton boll weevil. This enemy of a great 

 staple crop works in such a manner that it has 

 seemed beyond the usual means that have been 

 followed in insect control. In all except the 

 adult stage it is found within the fruit of the 

 cotton plant. For the greater portion of its 

 existence, therefore, it is at least as well pro- 

 tected as it would be if it occurred some dis- 

 tance below the surface of the soil. Even in 

 the adult stage the insect has habits that tend 

 to place it beyond the reach of man. As a 

 consequence, investigations of the insect that 

 have been carried on for several years have not 

 revealed a great number of direct remedial 

 measures. In fact, the destruction by burning 

 of the left-over portion of the crop and the 

 insects contained is the only direct means of 

 importance that has been devised. It is grati- 

 fying to note that recent investigations by 

 Mr. Wilmon Newell and Mr. G. D. Smith, of 

 the Louisiana State Crop Pest Commission, 

 published in Circular 33 of that commission, 

 reveal another direct means of control that 

 gives promise of general applicability. The 

 work of Messrs. Newell and Smith is of con- 

 siderable general interest, because it shows a 

 successful outcome from continued investiga- 

 tion leading from a suggestion revealed in 

 research. The investigators observed a clue 

 pointing toward the possibility of control and 

 directed all their energies toward the practical 

 perfection of the idea. 



For some years a cotton planter of consid- 

 erable prominence has been advocating vigor- 

 ously the use of paris green for the control of 

 the boll weevil. Though well-meant, his cam- 

 paign has been based upon a demonstrated 

 fallacy. Extensive tests that have been made 

 by various agencies have shown that the appli- 

 cation of this poison is by no means a prac- 



tical means of destroying the boll weevil. One 

 of the agencies that tested the use of paris 

 green was the Louisiana State Crop Pest Com- 

 mission, of which Mr. Newell is the executive 

 head. Although large and repeated applica- 

 tions did not result in increasing the yield of 

 cotton in the experimental fields, it was evi- 

 dent, both in these tests and in cage experi- 

 ments, that a number of weevils were killed. 

 Instead of stopping at this point, Mr. Newell 

 conceived the idea of determining wherein the 

 paris green was ineifective and how its action 

 might be increased. There were two impor- 

 tant difficulties to overcome. In the first place, 

 as paris green is now manufactured, a small 

 portion of free arsenic causes burning of the 

 foliage of plants. As the amount of the poison 

 applied is increased, this damage, though in- 

 sidious and at first scarcely noticed, becomes 

 greater until it is very serious. On this ac- 

 count increasing the amount of paris green in 

 the first experiments offered no hope as a prac- 

 tical remedy. The second obstacle encoun- 

 tered was the difficulty of forcing the poison 

 into the portions of the plants where a con- 

 siderable number of weevils would be likely to 

 obtain it. The mechanical structure of the 

 poisons in use prevented this. They were too 

 coarse for effective work. To obviate the first 

 difficulty, Mr. NeweU determined to use ar- 

 senate of lead, which can be applied in very 

 large amounts without any injury whatever to 

 the foliage. The second difficulty was over- 

 come by inducing a manufacturer to put up a 

 special, finely powdered form of the poison. 

 When this point was reached, a considerable 

 series of field experiments was outlined. These 

 experiments comprised about forty-six acres of 

 cotton to which the poison was applied, as well 

 as forty-nine acres provided as control areas. 

 The treated cotton in these experiments pro- 

 duced an average of 71 per cent, more than 

 similar cotton in the checks. In some cases 

 the net profit was even startling. In one case 

 a net profit of over $23 per acre was obtained. 

 A large portion of the effectiveness of the 

 application of powdered arsenate of lead in 

 the experiments was undoubtedly due to the 

 thoroughness with which the work was done. 



