57 



disciissetl in Alabama liiilleliii No. 178. This suinnici' 

 control will never be as great in Alabama as it is com- 

 monly in Texas under their drier summer conditions. 



Winter Control by Cold and Wetting. — The other 

 extreme of climatic conditions may also exert a very 

 important limiting elYect upon the survival ol weevils 

 during their liibernation period. This is most directive, 

 naturally in the extreme northern limit of their range, 

 and in western Texas. Oklahoma and Arkansas espec- 

 ially, has doubtless been the most eliective natural 

 factor in limiting the spread of the weevils. Occasion- 

 ally severe winter conditions seem to have reduced the 

 infested area but in no case has this winter extermina- 

 tion of weevils been as widespread or important as in 

 the case of summer control by summer heal an<l 

 drought. As a general rule winter conditions of un- 

 usual severity simply reduce the number of weevils 

 living through without really exterminating the spe- 

 cies and it is not possible therefore to measure accur- 

 ately the real value of such a control factor. 



Winter Temperatures Endured by The Weevils. 

 From a study of Weather Bureau records for many 

 years, it is ([uite evident that in western Texas, Okla- 

 homa and .\rkansas especially, the boll weevil has con- 

 tinued to exist, though in reduced numbers, in terri- 

 tory where the minumum winter temperature has fal- 

 len occasionally even slightly below zero Fahrenheit. 

 This does not mean that boll weevils can survive ac- 

 tual exjKjsure to zc-ro temperature, as the shelter with- 

 in wiiicli Ihey are passing the winter may so modify 

 • the outside temperature that the actual survivors do 

 not experience a temperature lower than 12 or 15 de- 

 grees above zero, F. Certainly where the winter mini- 

 mum rarely falls lower Idian 10 degrees F, it may be 

 expected that the weevils will survive the winter in 

 considerable numbers. The records for Alabama show 

 that during the past 24 years the winter minumum for 

 the State has fallen below zero only in seven years 

 and then it has been usually only in the extreme north- 

 western corner or in the northern portion of the State. 

 Weevils Now Exist North of Alabama-Tennessee 

 Line. — For several years now the weevils have main- 

 tained themselves at points which are farther north 

 than any point in Mississippi, Alabama or Georgia and 

 with the somewhat milder winters that occur in these 

 states, it is evident that there is no good reason to ex- 



