MOHTALirV IN !U)LLS VKKSTS S(,)rAI{KS. 35 



viviiiii: Ix'voiul six oi- s(^\(Mi (lays from tlic deposition of I he cltixs. - If 

 to this |)erccMltaiJ:(' \V(' add (he \2 pvv vrwi wliicli wci-c found dead 

 from st)ino caus(M)th{M- than \\\o \\\vvo imdci- coiisidcral ion. hut prin- 

 cipally duo to proliferation, we ha\(> a total mortality of from 7.") to 

 SO pvv cent. 



The avcM'ai^i* liMii^th of th(> d(»\(dopmental period from dune to 

 OctolxM- is shown in BnllcM in ol , l^ui-eau of I'JitomoloLTx , j)aL:e !i I. to he 

 hetwecn eitrhteen and twenty days. The mortality shown h\ these 

 records occurs, tluM'eforc*. duriiii^ th{> last two-thirds of the period 

 hi^ween tlu^ de|)osition of (he v^^^^ and tlu^ em(M-L:ence of the adult 

 W(V'\ il. When it is considered that a considerahle proportion of c^/,^^s 

 and \ cry younii: larva^ nuist also he destroyed, it IxM-omes increasinirlv 

 a|)|)arent that hut a very small percen(a<j:(» of the total mimher of 

 cii:trs d(»posited hy tlu* wcM'vils in a held of c()tt()n ])roduce adults. 



It may scorn that this tr(Mnendous (h^struction of weevil s(a*:es 

 would l)(^ sufFiciont to hrin^ the weevils under ])ractical control so 

 that the comparatively small remainder would produce^ little injurv 

 to the crop. Such, however, is not the case. The fact is that in 

 nc^arly if not quite all of the fields examined tlu^ weevils were so 

 ahundant as to destroy a large portion of the crop, and in most cases 

 it is ])rohal)ly true that the nudtiplication of the weevils was finally 

 limit(Hl hy the amount of food supply present rather than l)y the 

 destruction of the weevil stages by all these factors of natural control. 

 This does not mean that the crop did not benefit by the destruction 

 of w^eevil stages accomplished, for had it not been for this checking 

 of the possible multiplication of the weevils few of the fields could 

 have produced a crop that would have boon worth the picking. 



Were it not for the fact that in nearly all cases the destruction of 

 the weevil stage occurs only after the weevil has destroyed the cotton 

 form, the crop might bo much more largely benefited by this natural 

 control. Without^ the natural control existing, cotton ])roduction 

 within the weevil-infested area would be impossible; with it alone, the 

 continuance of cotton culture may still be possible; ])ut only by sup- 

 plementing the work of nature by the most practica))lo methods known 

 can the ])alance be thrown largely in favor of the ])lan(er in producing 

 a very profitable croj). 



NATURAL CONTROL IN VARIOUS LOCALITIES. 



In th(* sections of Table III the data are divided according to the 

 class of forms examined in order to make aj)j)arent (he varying dif- 

 ferences in the effects of tin* several factors of natural control upon 

 the weevil stages in each class of forms. In studying tlu^ combined 

 effect, which is really the measure of control in any locality and for 

 any period of time, this se})arati()n into (dasses is no longer necessary. 

 For this reason the figures given in Table VI re])resent a combination 



