124 



THE MEXICAN COTTON-BOLL WEEVIL. 



weevil- in a single season so that a crop may be obtained. This was 

 shown in a field which was under observation in Victoria County, 

 Tex., in 1906. It was found in April that a very large number of 

 hibernated weevils appeared in the field. This month was reasonably 

 moist, so that the cotton germinated promptly and made a quick 

 growth. The month of May, however, showed a decided deficiency 

 in precipitation, being more than 3 inches below the normal for the 

 month. This checked the weevil at the time the first infested squares 

 began to drop. The control continued during the month of June, 

 which also showed 3 inches less than the normal rainfall. These 

 conditions resulted in such a checking of the weevils by June that the 

 cotton plants were able to put on a large number of squares. The 

 month of July showed a precipitation above the normal, which caused 

 the plants to grow rapidly. The setback experienced by the weevils, 

 however, during the preceding dry period was so great that they 

 were unable to overtake the production of fruit, so that a yield of about 

 one-fourth of a bale per acre was obtained. 



Examples of such complete control within a single season are not 

 common. It frequently nappens that a drought continues so long 

 that the plants are seriously affected. In general, however, the 

 plants can recover more rapidly from a drought than the weevil. 

 This results in an advantage to the crop from even a short drought. 

 Of course the advantage becomes greater as the drought is prolonged, 

 provided it is not prolonged to a point where it seriously affects the 

 growth of the plants. Examples of the control of the weevil in one 

 season from heat and dryness of the preceding season are common. 

 Table LX shows a striking instance of this kind. It will be seen that 

 the effects of the drought of 1902 extended into the following season 

 and brought about a marked increase in production. By the follow- 

 ing year (1904) the recovery of the weevils from the drought of 1902 

 was indicated by a decreased production of cotton. 



Table LX. — General illustration of drought control of the boll weevil, Nueces County 



Tex., 1901-1904. 





Rainfall. 



Temperature. 



Cotton 

 produc- 

 tion, 

 Nueces 

 County, 

 equiva- 

 lent in 



500- 

 pound 

 bales. 





Annual. 



Mar. l-Aug.31. 



Annual. 



Mar.l-Aug.31. 



Year. 



Mean 

 aver- 

 age. 



Depar- 

 ture 

 from 

 nor- 

 mal. 



Mean 

 aver- 

 age. 



Depar- 

 ture 

 from 

 nor- 

 mal. 



Mean 

 aver- 

 age. 



Depar- 

 ture 

 from 

 nor- 

 mal. 



Mean 

 aver- 

 age. 



Depar- 

 ture 

 from 

 nor- 

 mal. 



1901 



Inches. 

 17.49 

 22 22 

 36! 92 

 28.54 



Inches. 

 -11.90 



- 7.98 

 + 6.72 



- 1.66 



Inches. 

 6.74 

 5.57 

 25.97 

 13.56 



Inches. 



- 7.42 



- 7.39 

 +11.38 

 + .83 



70.' 7 

 71.5 

 69.1 

 70.5 



°F. 



0.0 

 +1.4 

 — .9 

 + .4 



°F. 



76.2 



77.3 



74.5 



76.0 



°F. 

 +0.83 

 +1.85 

 - .9 

 + .5 



601 





480 







4,099 



1904 



1,556 





