INFLUE^'CE OF DKY SKASO.N C)>; fc^L'CCKKDl N (i SKASt^N. 15 



In connection witli this tabic it should !>(« noted thai the leinpeni- 

 ture conditions durin*:; tlu^ six months wliich aic of LTicatcst siLrnifi- 

 cance varied but little iVoin the normal. hi rainfall, howcxcr, a. 

 great deficiency occurred both in \\)()\ and in IDO'J. riidoiihtedly 

 the continuance of the drou<i:ht throULi:hout the season was more 

 influential than was tlu^ boll weevil in reducini:: the croi) for tlie Ncars 

 1901 and 1902, which were almost complete failures. ThrouLcli the 

 season of 19()o ther(^ f(dl a larij^e excess of rain and it was well (hstrib- 

 uted. This would ))r()du('e conditions \'ery faxorablc for wccNil 

 nudtiplication and injury, but in spite of this the cotton ciop for 19();> 

 for this county was nearly ten times as lari^e as durinu- the precedin<j: 

 year. In 1904 both temperature and rainfall were n(>aily nornud, 

 but the ellect of the hiv^^o number of weevils passim^: through hiber- 

 nation from the season of 1903 is very conspicuously shown by the 

 reduced size of the crop of 1904. This is an illustration of the cont rol 

 of the boll wee^^l by the unfavorable climatic conditions of an entire 

 season so effective that the weevil failed to become greatly- injurious 

 to the succeeding crop in a season when the climatic conditions were 

 unusually favorable for its increase. 



CONTROL BY WINTER CLIMATIC CONDITIONS. 



Exceptionally low' wdnter temperatures have occasionally proved 

 sufficiently effective to exterminate the weevils from certain areas 

 wdiich had become recently infested and within which the weevils 

 had not had time to become firmly established. This has been 

 illustrated by several well established cases in nortliern Texas and 

 Louisiana during the past few years. 



Weevils w^ere first found near Sherman, Tex., in the fall of 1903, 

 when the northern limit of the dispersion reached to within a few 

 miles of that place. No weevils could be found in that region in 1904 

 or until the dispersion of 1905 had taken place, thus proving that the 

 few wee\als reaching there in 1903 had failed to reproduce or that 

 they and their progeny w-ere completely exterminated by the winter 

 conditions of 1903-4. Weather Bureau records show that the 

 minimum temperature in this locality during the winter of 1903-1904 

 was 12° F. on January 26, 1904, and that the average monthly tem- 

 peratures for January, February, and March at Sherman wTre +2.6°, 

 + 10°, and + 6.9° above normal, respectively. It hardly seems prob- 

 able, therefore, that the weevils failed to maintain themselves in 

 this case solely on account of low winter temp(M'atures. 



