15G THE MEXICAN COTTON-BOLL WEEVIL. 



It is obvious that any method of controlling the boll weevil must 

 depend upon full knowledge regarding its life history and the natural 

 forces which tend to prevent' its multiplication. Certain practices 

 which upon superficial observation might be considered important 

 in the control of the insect upon investigation may be found to be 

 of no avail whatever. In fact, in some cases what appear to be 

 feasible means of control are worse than useless, because they tend 

 to nullify the effects of natural forces which act against the weevil. 

 This is notably the case with the practice of attaching a bar to a 

 cultivator to jar the infested squares from the plants. As will be 

 explained later, this practice is of advantage only under very restricted 

 conditions. Throughout the greater part of the infested territory it 

 is an assistance rather than a hindrance to the boll weevil. 



There are seven features of the life history of the weevil that are 

 of cardinal importance in control. These are indicated below. 



1. The weevil has no food plant but cotton. 



2. The mortality of the weevil during the winter is very high. 



3. The emergence from hibernating quarters during the spring is 

 slow and prolonged until well into the summer. 



4. Early in the season, on account of comparatively low tempera- 

 tures, the development of the weevil is much slower than during the 

 summer months. 



5. The drying of the infested squares, as the result of heat, soon 

 destroys the immature stages of the weevil contained therein. 



6. The weevil is attacked by many different species of insect ene- 

 mies, the effectiveness of which is increased by certain practices. 



7. The weevil has but little ability to emerge when buried under 

 wet soil. 



Exactly how each of these features of the life history of the weevil 

 affects plans for practical control will be explained in the following 

 paragraphs. 



In the case of many of the important injurious insects the problem 

 of control is greatly complicated by the fact that the pests can sub- 

 sist upon more than one food plant. In some cases a single species 

 attacks several cultivated crops. In other cases the pests can sub- 

 sist upon native plants practically as well as upon the cultivated 

 species. All these difficulties are absent in the case of the boll-weevil 

 problem. As has been shown in the preceding pages, the insect is 

 absolutely restricted to the cotton plant for food and for opportu- 

 nities for breeding. The problem is therefore much more simple than 

 it would be if the weevil could subsist upon any other plant in the 

 absence of cotton. This peculiarity of the weevil was the basis of 

 the recommendation made in 1894 that the pest be exterminated 

 absolutely in the United States by the abandonment of cotton. At 

 that time only a few counties in Texas were affected. The procedure 

 would have involved small expense. Even now the weevil could be 

 exterminated in a single season by preventing the planting of cotton 

 and the growth of volunteer plants. This proposal has been made 

 at various times, notably at the national boll-weevil convention held 

 in Shreveport, La., in 1906. 



Various difficulties, however, appear to render the plan entirely 

 impracticable. In the first place, there would be strong opposition 

 in large regions in Texas where the planters have learned to combat 



