26 Growing Sea Island Cotton Under Florida Conditions 



and certainly from Ocala south, live basal sprouts in many 

 of the Sea Island cotton fields will be comparatively common 

 throughout the winter. This complicates the problem of wee- 

 vil control and the following year's weevil supply will be great- 

 ly augmented by these fields. Moreover, in many instances 

 weevils will migrate from stubble fields into the young cotton 

 during a period in which it otherwise would not have to be 

 poisoned, the latter part of June or the early part of July, 

 for instance. It can almost be said with safety that the early 

 destruction of the cotton stalks will not only be very beneficial 

 in the southern part of the Florida Sea Island Belt, but that it 

 will be a practical necessity once the boll weevil becomes well 

 established there. 



Natural Control 



It has been estimated that the progeny of one pair of weevils 

 in a single season would be 12,755,000 individuals if nature 

 had not provided several means of preventing excessive multi- 

 plication. The most effective of these are the extremes of tem- 

 perature and insects that prey upon the weevil. 



Lov^ Winter Temperatures 



Low winter temperatures, in the northern part of the Cot- 

 ton Belt, probably give more protection against the boll weevil 

 than any other factor. In Florida, however, this is not the 

 case. Even in the northern tier of counties, winters are never 

 severe enough to be of major importance. 



In the lower Sea Island producing counties, the unusually 

 warm winters are an important factor in reducing the weevil 

 population. During long warm periods the weevils become 

 active, and, if no cotton is available for food, soon die. 



High Summer Temperatures 



High summer temperatures, on the other hand, are an im- 

 portant factor of natural control in all parts of the State. 

 During the ten to twelve days that the immature weevil lives 

 in the square on the ground, heavy mortality is produced by 

 high temperatures. Sometimes practically an entire genera- 

 tion of immature weevils is wiped out by hot sunshine. In 

 Florida it is the most important single factor of natural con- 

 trol. 



Parasites 



The boll weevil has a number of natural enemies in Florida. 

 Several parasites deposit eggs on the immature weevil stages 

 in squares. The young parasites that hatch feed on the imma- 

 ture weevil stages and kill them. Parasites, however, do not 

 destroy a very large percentage of the boll weevils in Florida. 



