a- .,:a-lr- ..,_
FleoULAR No 146.
'weutc I dl February 12. 1912
3 United States Depgriculture,
BUREAU OF ENTOMOLOGY.
L 0. HOWARD. EKu..ni..nuhlncii andl tir .11 d liii raLU.
Il: TEE MOVEMENT OF THE MEXICAN COTTON BOLL
if pWEEVIL IN 1911.
I. rg f By W. I). HUNTER.
"S he:i ft harge of South#'n flie l n 'eie lnd Ing '..lir tli,. oa.
During the season of 1911 the bIoll weevil wit,- greatly reduced in
Jl burs throughout its entire range. This resulted from a coni-
ation of climatic influences extending over a period of about
years. So unfavorable were the conditions that the insect
Exterminated in an area covering about 23.000 square miles in
northwestern portion of Texa, and the western poi-tion of Okhi-
aoX. Undoubtedly these condition., had an important bearing on
| production of the large crop of 1911.
The unfavorable condition, for thle weevil which culminated in
911 began in 1909. In that year drought occurred in Texau and
I isiana at such a time a- to check the development of the immni-
|i.i stages. In 1910 equally adver-se conditions prevailed, and tle
"l 5f was further reduced in numnelwrs. At the end of the season of
0B conditions arose which gave thle inset another veiy important
,hac[k. This was a killing fro.t which occurred October 29. The
rsvils were deprived of their food in all l)frt" of tlhe infested terri-
SGory except along the Gulf Coa.t and in it few i-4,liti'd localities el.e-
w here. The freeze destroyedI outright ,n)IuhI0-II, iunil)ers of the
t *eevils which were found ill the holls an;ti 4inuare.s. but the conditions
H.: *" -ez eeev nna inr ti e
I:. immediatelyy following the freeze were even UKi important, in re-
i. during the infestation to a v'er low point. After the freeze of Octo-
r29 the weather became warm, and this induced activity on the part
i f the weevils that survived. In fact. temperatures occurred for
several weeks which caused the insects rtire food. An active
search for food began, but as the cotton hail lied the ma-
jority of the weevils which had survived t t e e, .0 o
food and perished. ./ ,, ,'
24775*-Cir. 1468-12 / -. . /
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TH Mf WMV Vf M .. ..L
The general effee f the cold of Ot44 29 is shown by a study of
the conditions in ccL4fAitcalities whfc>1(ere exempt from freezing, :
temperatures. In se\tral countieJs4 li6jicinity of Cisco, Tex., for
some unexplained reafuni the first killbqf frost in 1910 did not occur '
until November 29. :AyttAs-infednost.-f the weevils were in hiber- m
nating quarters. As a resultW 191,,i 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
The great reduction in the number of weevils which succeeded in :X
passing the winter of 1910-11 is shown by hibernation experiments ..i
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 su-
vival during seven different seasons in seven widely separated locali- :i
ties in Texas and Louisiana has been 7 percent.
SThe 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. "J|
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 *3
weevils started on their dispersion flight, encountered fields which :m
had been stripped by the leaf worm, and continued their flight indefi- i
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-
Fz(, 1. -The qr+.ntd od the cotton I,,Il weeviI from 1892 to 1911. (I)rILgniiI. I
UNIVERSITY OF FLORIDA
3 1262 09216 5827
THE MOVEMENT OF THE BOLL ..... .,..
tion in 1911 that there is any hope whatever for a pera
tion in the importance of the boll weevil. On the cot4q
essary for planters to continue their fght against the pi
to the plans that have been detailed in the publications i
ment of Agriculture.
S JAMES WILSON i
Secretary of Agricdture. -
WASHINGTON, D. C., January 3, 1912. .:
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