22 PAPERS ON THE COTTON BOLL WEEVIL^ ETC. 



appeared on May 18, in 1904 on May 23, and in 1901 on May 10-15; 

 but as the intervals between pickings were a week or 10 daj^s it would 

 seem safe to judge that the normal time for the maximum number to 

 emerge at Vienna is about May 15 to 20. It will also be noticed that 

 the weevils appear much more rapidly and early on early planted 

 cotton, but the maximum number does not appear at the time of 

 squaring of the earliest planted cotton, but at about the time of squar- 

 ing of the main crop, thus giving a decided advantage to the early 

 planted cotton. The determination of the exact time of the emergence 

 of the maximum number of weevils will be practically the same as 

 that for the time of maximum oviposition for the hibernating brood, 

 concerning which see page 25, and which in Lavaca County will ror 

 mally occur about May 20, at College Station about June 1, and in 

 northern Texas probably about June 10. 



PREVENTION OF HIBERNATION. 



It may be readily seen from the foregoing discussion that any 

 methods which will reduce the number of weevils going into hiberna- 

 tion in the fall are of the utmost importance in the control of the 

 pest, inasmuch as nature aids in further reducing their numbers dur- 

 ing the winter. All students of the problem of boll-weevil control 

 have agreed that in this prevention of successful hibernation lies the 

 most effectual means of reducing the numbers of the weevil and pre- 

 venting injury the next season. Two methods are advocated: (1) The 

 destruction of the stalks in the fall as long before frost as possible, 

 and (2) rotation of the cotton crop, planting on land not in cotton the 

 previous year and as far from such land as is possible. 



FALL DESTRUCTION OF STALKS. 



By the destruction of the stalks as early as possible in the fall the 

 number of weevils entering hibernation is reduced in several wa3^s: 

 (1) All immature stages in the squares and bolls, which might develop 

 into weevils if the stalks remained standing, will be destroyed. (2) 

 Probably three-fourths of the adult weevils in the field at the time of 

 burning may be destro3^ed if the work be proper!}^ managed. (3) By 

 clearing the field of cotton some time before the normal time when 

 weevils will enter hibernation their food is destiwed and the adults 

 either starve or migrate to other fields. Were this work done uni- 

 formly over a considerable area, the weevils w^ould surely starve, 

 as they can not be forced into hibernation before the normal time. 

 That a large mortality follows if this is attempted is shown in our 

 records (see pages 2-3). These advantages are apparent, tho but few 

 actual records of the benefit of su(^h fall destruction of stalks have 

 been published. From the conditions under which experiments must 

 be made it is difficult to demonstrate in a tangible way the actual 



