14 WEEVIL-RESISTING ADAPTATIONS OF COTTON. 



in order to put an end to the breeding of the weevils. It would 

 then become practicable and desirable to regulate planting so as to 

 bring the growing period of the cotton at the most favorable season 

 for a rapid development of the crop, and thus to give the weevils 

 the shortest possible opportunities for breeding. If the fall and 

 winter had favored the survival of many weevils, planting could well 

 be deferred until the weevils had disappeared, a fact which could be 

 ascertained b} 7 starting early a few observation plants from which 

 the weevils could be carefully picked by hand as long as they con- 

 tinued to appear. 



The extent of the mortality of the boll weevil in the spring has been 

 well shown in the investigations reported by Mr. W. D. Hunter on 

 the effects of applying Paris green to the very young cotton as a 

 means of destroying the weevils which had lived through the winter. 

 Numerous dead weevils were found in the poisoned fields, but equal 

 or even greater numbers were found in those to which no Paris green 

 had been applied, and the conclusion was drawn that a large propor- 

 tion of the weevils, which pass the winter in a state of hibernation 

 or torpidity induced by the cold, perish through starvation or other 

 causes in the spring, after the weather has become warm enough to 

 render them active again and permit them to renew their search for 

 cotton plants on which to feed and lay their eggs. & 



It is easy to understand, too, that after the weevils have been re- 

 duced by the cold to a condition of inactivity involving an almost com- 

 plete suspension of the vital functions, the lack of food and the lapse 

 of time can make very little difference with them. Starvation comes 

 much quicker during warm weather while they are going actively 

 about, so that it is the autumn and spring, which must be relied upon 

 to reduce the numbers of the weevils rather than the cold periods of 

 the winter months. Messrs. Hunter and Hinds have also noted as 

 significant the fact that of Aveevils captured at the middle of Decem- 

 ber, 15.8 per cent passed the winter successfully, while of another lot 

 captured a month earlier, only 1 per cent survived. Their conclu- 

 sions were as follows: 



It is evident that the weevils which pass the winter and attack the crop of 

 the following season are among those developed latest in the fall and which, in 

 consequence of that fact, have not exhausted their vitality by oviposition or any 

 considerable length of active life. 



With these facts in mind it becomes plain that no objections need 

 be raised on general biological principles to the introduction of new 



«A determinate variety of cotton would also avoid the cultural disadvan- 

 tages incidental to very early planting, for if the weather happens to turn 

 cold and wet the cotton is often either killed outright and has to be replanted 

 or, what is still worse, it becomes permanently stunted and unproductive. 



& Hunter, W. D., 1904. The Use of Paris Green in Controlling the Cotton Boll 

 Weevil, Farmers' Bulletin No. 211, U. S. Department of Agriculture. 



