12 HIBERNATION OF THE COTTON BOLL WEEVIL. 



and 20. By this time practically all of the crop which can be expected 

 will have been set and many of the oldest bolls will be found maturing. 

 If a moderate crop t)f bolls is being matured the formation of squares 

 usually ceases, almost if not entirely, for a period of several weeks. 

 Whereas in the early part of the season female weevils could find 

 abundant opportunities for depositing their eggs in previously unin- 

 fested squares, after the time of total infestation is reached such 

 opportunities practically cease to exist. The available supply of 

 squares and bolls becomes too small to support the large number of 

 weevils which may be present, and conditions become decidedly 

 unfavorable for their further multiplication. It is at this season of 

 the year, usually from August 15 to September 20, that the largest 

 general dispersion movements of the weevils take place. It is at this 

 season also, during recent years, that the cotton leaf-worm has 

 become sufficiently abundant to secure a partial or complete defolia- 

 tion of the plants. While the occurrence of the leaf-worms is by no 

 means regular, the effect of their work is to still further limit the 

 available food supply of the boll weevil and to force them into a more 

 general dispersion from the defoliated plants. On account of the 

 reduced supply of squares, the increased period of development in 

 bolls, and the extensive dispersion movements of the weevil at this 

 season of the year, it usually happens that the actual number of 

 individuals in a field becomes greatly reduced. 



Following the maturity of a considerable portion of the crop of 

 bolls, and usually in connection with the occurrence of a heavy rain- 

 fall, a renewed growth of the plant commonly produces an abundance 

 of squares. It is this late top growth of the plant, which serves no 

 good purpose so far as further production of cotton is concerned, 

 that is primarily responsible in most fields for the needlessly large 

 number of weevils produced between the time of maturity of the 

 crop and the usual time of destruction of the plants by frost. A 

 large proportion of the weevils which become adults before Septem- 

 ber 1 may be expected to die, either as cold weather comes on or 

 during the early part of the winter season. The later-developed 

 weevils, however, have not exhausted their vitality and are much 

 more likely to survive the full hibernation period. The importance, 

 therefore, of preventing or of reducing the formation of squares 

 following the period of maturity of the bolls can be easily appreciated. 



To sum up briefly the principal points in the development of 

 weevils which may enter hibernation, we may say that from the 

 beginning of the formation of squares until the plants are destroyed 

 by frost the development of the boll weevil is a continuous 

 process. During the usual fruiting period of the plant it is possible 

 that as many as eight generations of the weevil may be produced, 

 especially in southern Texas. It is also possible that during this 



