INFLUENCE OF PERIOD OF INFESTATION. 53 



to account for the disparity if the conditions of exposure to the sun- 

 shine were at all similar. The difference of 3.5 per cent among the 

 hanging forms is not great and it seems reasonable to assume that a 

 generally more dense shade may have protected the fallen forms in 

 Louisiana. This would possibly favor ant work but be unfavorable 

 for destruction by heat and by parasites in fallen forms. 



From Table X, as a basis of comparison of areas which have been 

 infested for different periods of time, it appears that in the territory 

 infested but about two years the parasite attack amounts to only 

 about two-thirds as much as it does where the weevils have been 

 present for an average of five years. In neither case are they suffi- 

 ciently abundant to be considered as a factor of great importance at 

 present, but recent experiments indicate that it may be possible to 

 greatly increase their utility, in the future. The Solenopsis ants do 

 .not seem to require a long period of time to become accustomed to 

 the weevil's presence, but attack the stages readily and probably in 

 proportion to the abundance of the ants. It would seem that the 

 effectiveness of heat may have been increased by the methods of 

 cultivation of cotton which have been adopted by the planters in the 

 older infested region in Texas. 



EFFICIENCY OF NATURAL CONTROL IN VARIOUS SECTIONS. 



In the sectional reports of the Weather Bureau for Texas the 

 localities from which observations are reported are divided into seven 

 sections, according to their geographic location and their simi- 

 larity in regard to climatic conditions. In making a more detailed 

 locality study of the natural control of the boll weevil, it seems 

 advisable to group the localities which have been examined upon the 

 same general basis as has been done in grouping them for weather 

 observations. The first two groups, western Louisiana and eastern 

 Texas, have very similar conditions of climate, soil, flora, and fauna. 

 In the group designated as southern Texas are found those localities 

 which are included in the Weather Bureau reports as in the ''coast" 

 district, together with Cuero and Hallettsville from the ''south- 

 western" district. These localities would seem to be more closely 

 identified with the conditions of the coast district than with those of 

 southwestern Texas so far as weevil conditions are concerned. For our 

 present purposes, therefore, we have formed five groups of localities in 

 Texas and one in western Louisiana. It is somewhat unfortunate 

 that the limitations of the printed page prevent the association of all 

 the data which should be considered in a study of this kind, and it is also 

 realized that it is a difficult matter to make comparisons and to draw 

 conclusions from a table even as extensive as is Table XI. We believe, 

 however, that it is better to present these data, so that anyone who 

 may care to study the subject more fully than can be done id this 

 bulletin may have the opportunity of referring to these figures. 



