96 INSECT ENEMIES OF THE BOLL WEEVIL. 



IV. Tlie cultural methods of controlling the cotton holl weevil are the 

 most favorable methods of cotton culture from the parasitic standpoint. 



The tendency of the principal boll- weevil parasites to prefer light 

 and heat leads immediately to a long series of recommendations. 



Heat on the ground is essential for the climatic control of the 

 weevil and also for parasitic control. Although the two factors 

 overlap, each accomplishes considerable independent control. 



A heated condition of the ground may he accomplished hy planting 

 the rows far apart, hy checlc-row planting, hy flat cultivation, or hy 

 planting varieties which have short limhs, or shed their foliage early, or 

 have small leaves. 



Fall destruction of the cotton plants cuts off the parasites from 

 breeding on the weevil but sends them to other hosts upon which 

 they can breed a winter generation, or pass hibernation, thus gaining 

 not only a generation on the weevil but providing for themselves 

 during the winter. 



The early planting of cotton in the spring makes it possible for the 

 earliest parasites to attack the weevil. 



V. The tendency to retain infested fruit, which is displayed by 

 certain varieties, is worth consideration. 



The fact that many more parasites are reared in hanging squares than 

 in fallen squares makes it desirable in humid regions to have many of 

 the hanging squares in afield in order to serve as a nursery of parasites 

 for the weevils in the fallen squares. 



Varieties which show an elongate diagonal connection between 

 the square and stem will tend to have an imperfect absciss layer 

 formed. Prominent in this class are the cluster boll varieties of 

 cotton. It is recommended that search he made for such a variety as 

 will retain its infested forms and at the same time fulfill the other require- 

 ments in the making of a good crop. 



VI. Any step which will diminish the number of weevils and not 

 diminish the number of parasites in a field will of course increase the 

 percentage of parasites present. 



The most important step of this kind is the collection of infested squares 

 and placing them in cages with a screen through which the weevils can not 

 escape hut the parasites can. 



Ant colonies may be introduced into the fields in boxes of fresh 

 manure. 



If squares are collected, they should not he burned, hut should be placed 

 in screened cages. 



