30 



By platting the temperature curves for different points it will be 

 seen that the mean daily temperature falls below 60 about December 1 

 at Victoria. Tex. (which agrees with the observations of Hunter and 

 Hinds), at College Station about November 10 to 15, at Dallas several 

 days earlier, and for the northeastern jjart of Texas about November 5. 

 From a brief study of the availal)le data, which we are having tabu- 

 lated and expressed grajDhically, we believe that these dates will be 

 found to coincide very closely with those of the first killing frosts 

 for these sections, although the frost dates Avill fluctuate much more 

 widely from year to year than does the mean daily temperature. 



In carefully observing the numbers unci activity of the weevils 

 every day during the fall, it Avas interesting to note that the activity 

 was immediately arrested whenever the mean daily temperature 

 drop])ed below (50'^, and a comjiarison of this daily record with the 

 U'ni[)erature curve })latted for College Station shows this strikingly. 



The number of weevils entering hibernation will depend almost 

 entirely upon the food supply during the fall. Whether there are 

 one or two more broods in one part of the State than another matters 

 not, for after the third brood the weevils become so abundant that 

 their numbers are limited only by the available food supply. There- 

 fore, with a normal or excessive rainfall during September and early 

 October, whicli would cause the plants to s(iuare freely, there would 

 be an abundant food supply and many more weevils entering hiberna- 

 tion than in a dry year when but few squares are formed. The 

 weather of the fall, then, has a considerable influence on the number 

 of weevils which commence reproduction the next spring. 



At present one of the most important natural factors in reducing 

 the food supply of the weevils in the fall is the leaf worm, or so-called 

 •' army worm " {Alahdma arg^llac^ea^lA^\\hn.) . It is a most interesting 

 entomological phenomenon that this insect, which formerly did so 

 many million dollars' worth of damage to the cotton of the South and 

 which was the subject of much iuA-estigation, has now become one of 

 the Texas cotton planter's most valued allies and is welcomed by him 

 wherever the weevil occurs. That the defoliation of the plant by 

 these caterpillars has an important influence on the number of weevils 

 hibernating is certain. 



Of course, the same results are accomplished by thoroughly grazing 

 the cotton, or better, by cutting and pulling the stalks, and the 

 latter forms the most important feature in the fight against the pest, 

 as discussed hereafter. As far as we can ascertain, the number of 

 weevils entering hibernation Avill average about one j^er stalk: in 

 badly infested fields it will often be two per stalk, and it may be as low 

 as one to two stalks, with cotton planted an average distance apart. 



Where the stalks are allowed to stand, many of the injured bolls 

 remain on them unopened during the winter, and in these the imma- 



