SECTIONS IMtOFiriNC MOSI' 15 V NATrilAl. CnNlltol.. (\:^ 



Afanv of tho conclusions which niiirlit he drawn from Tal)lc XI IF 

 have ah-cady ])ccn stated in connection wiih |)rcccdini^ tal)lcs. The 

 last column shows that southern Texas enjoys the hen(«fils of imlural 

 control to a lari:(^r(h\ixree than (h)(\s any other sect ion. In that section 

 62.6 ])er cent (nearly two-thirds) of all stages found had heen de- 

 stroyed. Onc^ lialf of this mortality was accomplished hy ants, the 

 other half hy heat and |)arasit(\s cond)ine(l. Central Texas stands 

 next, with a total mortality of !.").") per c(Mit. In this section, while 

 the effectiveness of lu^at and of ants had decreased, that of j)arasites 

 had consideral)ly incrcnised. The increase in parasite attack, however, 

 was hy no means sudicicMit to counterhalance the (hM-rcase from \\w 

 other two factors. Western Louisiana and eastern Texas, with l.J.'i 

 and 41.4 per cent of total mortality, resj)ectiv(4y, show ver\' closer 

 a*:reenient in the proportions of mortality from each factor. This 

 close airreement might ])c anticipated because of the similarity in 

 soil, climatic, and cultural ccmditions prevailing in those adjacent 

 sections. The principal reason for separating the localities into 

 these two sections was to facilitate a comparison of the recently 

 infested territory of Louisiana with the older-infested sections of 

 Texas. In this respect, also, but little difTerence exists between east- 

 ern Texas and western Louisiana. In analyzing the factors producing 

 the closely similar total percentages of mortality in western Louisi- 

 ana and in central Texas it will be seen that there w-ere very essential 

 differences. In western Louisiana nearly 70 per cent of the total 

 mortality found was due to ant attack, while in central Texas only 

 43.0 per cent was due to ants. It is evident that in central Texas 

 may be found the conditions which are most favorable to parasite 

 attack. An extended study is being made of the entire field of para- 

 sitic attack upon the boll weevil, and part of the results previously 

 obtained may be found in Bulletin 73 of this Bureau. By far the 

 lowest prop(^rtion of total mortality is that foiuid for southwestern 

 Texas. ^lost of the localities hicluded in this section have but 

 recently become infested. It would appear, however, that in the 

 higher altitude of those localities heat ma}' not be quite as effective 

 and that ants may not be as abundantly distributed as they are in 

 other sections of the State. The observations in this locality have 

 not extended over a sufficient period to justify any general conclu- 

 sions regarding the result of the smaller degree of natural control 

 which would appear from the observations made. It is quite possible 

 that other factors than these which are here considered nniy serve to 

 check the weevil in this section. Such a condition as a much larger 

 mortality during the hibernation period might hold the weevils largely 

 in check in spite of the smaller mortality (hiring the summer. 



