2 THE MOVEMENT OF THE BOLL WEEVIL IN 1911. 
The general effect of the cold of October 29 is shown by a study of 
the conditions in certain localities which were exempt from freezing 
temperatures. In several counties in the vicinity of Cisco, Tex., for 
some unexplained reason, the first killing frost in 1910 did not occur 
until November 29. At this time most of the weevils were in hiber- 
nating quarters. Asa result, in 1911, 1t was found that in the vicinity 
of Brownwood there was an area in which the weevils were numerous 
and in which considerable damage was done. This area corresponded 
exactly with the area in which the freeze of October 29 was not 
experienced. 
The great reduction in the number of weevils which succeeded in 
passing the winter of 1910-11 is shown by hibernation experiments 
which were conducted at Tallulah, La. At this place it is determined 
- that one-half of 1 per cent of the weevils which entered hibernation 
emerged in the spring of 1911. In favorable seasons as high as 12 
per cent have survived in that locality and, in fact, the average sur- 
vival during seven different seasons in seven widely separated locali- 
ties in Texas and Louisiana has been 7 per cent. 
The region in which the boll weevil became exterminated in 1911 
is the one in which the conditions of drought were most intense in 
1909 and 1910 and in which at the same time the conditions for 
hibernation are less favorable than in other parts of the cotton belt. 
The territory where the loss occurred consists generally of open 
country in which but little timber is to be found. 
Notwithstanding the great reduction in the numbers of the boll 
weevils in the United States in 1911 considerable advance was made 
to the east and north when the dispersion movement began in August. 
The explanation of this lies in the outbreak of the cotton caterpillar, 
which defoliated practically all of the fields throughout the infested 
area at about the time the dispersion movement was beginning. The 
weevils started on their dispersion flight, encountered fields which 
had been stripped by the leaf worm, and continued their flight indefi- 
nitely. If the fields just beyond the border of the previously infested . 
territory had not been defoliated the weevils would have stopped and 
the total area covered would have been much less. 
This extensive dispersion of the insect caused it to regain much of 
the territory it had lost in Texas and Oklahoma, and Florida became 
invaded for the first time. (See map, fig. 1.) 
The reasons for the great scarcity of weevils in 1911 are plain. 
The reduction was due to a combination of climatic influences 
which can only be expected to recur at very infrequent intervals. 
With the return of seasons favorable to it the boll weevil will un- 
doubtedly regain all of the lost territory and multiply to the same 
extent as it has in the past. It must not be supposed from the situa- 
