Sl'.M.M.\i:\ AND ('(INCI.ISIONS. 



SUMMARY AND CONCLUSIONS 



ir {\\cvo ])o a fair ainoimt of moist tire in 1 lie soil dp to t lie t iiiic s(|iiar('s 

 boj^iii to I'oi-m. and \\\cvc tlicii ciisiics a pcfiod of fioni foui- to >i,\ wcck^ 

 of hot dry wcat Ikm, w ith mean avt'raice tcinpcratiircs i-an<:inL,^ IVoin 75 

 to S ") dogrocs F., it may hiMwjxM'tcMl thai ihcwccxils. llioiii^h ahiiiuhaiit 

 thorotoforo, may be so oll'cctivcly chcckcMl as to do little iiijni\ lo tli(>, 

 crop of tliat season. 



An iMitire season of extrtMue (h'oiiirht, excii \\ithoiit exccj)! ioiiallv 

 hiirii tcmperatunvs. will i^reatly reduce tlic inimhcr of \\cc\ ils. hut the 

 crop will be small because of the continued lack of moisture. This 

 conchtion may show little l)enefit from weevil control diiriiii:; that sea- 

 son, but will tT^reatly favor tlu^ production of a larire crop, if weather 

 conditions be favorable, dui-in<^ t he followin^j^ season. The diirerence in 

 effect of a droui]:ht dm-ing s(piarin<2^ season alone and durin<:; the entire 

 season li(^s in the widely different effect which those conditions exert 

 U})on the number of w-eevils developed in the fall, upon the food sup- 

 ])ly available to the weevils imtil time for them to enter hibernation, 

 and upon the shelter obtainable by the weevils dTu-inci: winter. In 

 the former case many w^eevils may survive, in the latter few w('e\'ils 

 will survive to attack the succeeding cro]). 



Winter conditions of imusual severity with frequent low tempera- 

 tiu'es and much rainfall have a beneficial effect by reducing the num- 

 ber of weevils surviving hibernation and by preventing the siu'vival 

 of old cotton roots. 



By cultural practices it is possible to secure regularly as great 

 reduction in weevil injury during the following season as occurs 

 occasionally after winters of extreme severity. 



Defoliation of cotton by the cotton leaf worms, if thorough and 

 repeated, may be a ver}^ important factor in reducing the number of 

 weevils in a field which may enter hibernation, or which are likely 

 to survive. The planter can usually secure regularly nmch of the 

 good effect of irregular leaf worm defoliations by destroying the 

 cotton stalks early in the fall. 



Fallen forms contain fully 70 per cent of the w^eevil stages develop- 

 ing in a iield. These stages are exposed to the most effective action 

 of heat and of ant attack. Onl}^ in case of the fallen forms is it pos- 

 sible to YSLvy cultural practice so as to increase the effectiveness of 

 these factors. The mortality occurring in fallen forms is fully four 

 times as effective in controlling the weevil as is that in hanging forms. 



Less than one-half of all the w^eevil stages w^re still alive when 

 found. If these had been allowed to remain undistiu'hed. nndcM' the 

 continued influence of the three factors of natural control studied, it 

 is very probable that the total mortality resulting would fmally have 



