» HIBERNATION OF THE COTTON BOLL WEEVIL. 



Foremost among the points of immediate practical application 

 shown in this bulletin is the enormous importance of the fall destruc- 

 tion of the plants. This has been one of the recommendations of the 

 Bureau of Entomology for some years. Its importance will increase 

 rather than diminish in the regions now invaded by the insect. The 

 cage experiments at Dallas, Calvert, and Victoria, Tex., in the winter 

 of 190G-7 have given most important and accurate data showing 

 exactly what may he accomplished by the fall destruction of the 

 plants at various dates. This bulletin, moreover, shows the most 

 favorable and least favorable conditions in the hibernation of the 

 weevil. This information can be put to pracl ical use by every farmer 

 in the infested area. It shows exactly where tin 4 most effective work 

 can be done. A not unimportant feature is the showing of the abso- 

 lute impracticability of late planting to obviate damage by the boll 

 weevil by reason of the remarkable longevity of hibernated individuals 

 without any green food whatever. 



The information included in this bulletin has been accumulated 

 through the investigations and observations of the numerous agents 

 connected with the work during the seasons of 1902-1907. Some of 

 the facts have been briefly stated in previous publications, particularly 

 Bulletins 45 and 51. The manuscript for the present publication was 

 prepared during the summer and fall of 1907, and since that time 

 some of the conclusions drawn from this study have been published in 

 connection with other bulletins and circulars relating to the weevil 

 and its control. But in no other instance have all of the facts been 

 considered or their complex, intimate, and important co-relationships 

 studied as in this work. 



On account of the large amount of work that has been done and the 

 practical importance of many of the conclusions drawn it has been 

 considered that full indication should be made in the bulletin of the 

 methods by which the conclusions and recommendations are reached. 

 Therefore special pains have been taken to give all essential data and 

 to represent by charts matter that can thus be graphically expressed. 



It will be noted that the various experiments dealt with in this 

 bulletin are taken up according to the years in which the work was 

 carried on. The result is that some special topics, such as time of 

 entrance into hibernation, will be found discussed in several places. 

 It has been found entirely impracticable to follow a strictly topical 

 system and discuss each point connected with hibernation witli refer- 

 ence to the work of the various years. This impracticability is due 

 principally to the great natural variations in the seasons. Never- 

 theless the first part of the bulletin discusses the general feature of 

 hibernation and the summary at the end has been written in such a 

 way as to bring the principal conclusions on the various topics into 

 condensed form. 



