398 SOUTHERN FIELD CROPS 



or otherwise destroying, as much as practicable of the litter 

 and vegetation adjacent to cotton fields and the advisa- 

 bility of keeping the fields in a clean and neat condition. 



367. Principal preventive measures. The boll-weevil 

 in its different stages spends most of its life within the cot- 

 ton forms, and when outside it takes so little food from the 

 surface of boll or square or leaf, that the use of poisons 

 (except in one special case, as indicated below) is useless. 

 The warfare against this pest must be an indirect one, 

 and its aim should be to prevent many insects from living 

 through the winter. 



When cold weather approaches, or on the occurrence of 

 a killing frost, boll-weevils enter their winter quarters 

 under all sorts of trash. Experiments have shown that 

 if the weevils can be deprived of their food for a period 

 of several weeks before cold weather occurs, they will be 

 .so weakened that most of them die before spring. Hence 

 the best method of reducing the injury in the next crop 

 of cotton consists in plowing, piling, and burning in Oc- 

 tober, or as soon as possible, the old cotton stalks and all 

 litter adjacent to the cotton fields. Even later burning is 

 beneficial, though to a less extent. Burning the stalks 

 and burs destroys the immature insects inside the bolls and 

 squares, destroys many of the adult insects, and deprives 

 the remainder of food and shelter. 



Preparatory to being burned, the cotton stalks are usu- 

 ally uprooted with a double moldboard plow. A special 

 device for cutting the stalks below the ground is shown in 

 Figs. 174 and 175. 



A less effective treatment consists in turning a large 

 number of cattle into the cotton fields before frost, so that 



