OF WASHINGTON, VOLUME XIII, 1911, 113 



It now appears that the average developmental period at Alex- 

 andria, Louisiana, in 1908, in August, was 15.3 days in fallen 

 squares and 15.1 days in hanging squares. It is probable that 

 in drier localities there would be still a greater difference in 

 the average development. 



It has always been necessary in our studies to separate our 

 studies of weevils in the squares from those of weevils in bolls 

 because the development in bolls is always much longer than 

 in squares, in some cases being almost twice the average in 

 squares. This may be considered as a combination of the 

 factors of lower temperature, greater humidity and tougher 

 food. 



One of the most interesting factors which has been ob- 

 served in the study is that of the period preceding the falling 

 of the squares to the ground. It is of course apparent that 

 when a cotton square hangs on the plant a little longer than 

 other squares it becomes drier, as it has not the benefit of the 

 shade and moisture of the ground. The effect of the period 

 before falling upon the development is much stronger than 

 would be expected. A few examples may be cited to illus- 

 trate this point. At Victoria, Texas, in 1904, in the first 15 

 days of July, the average developmental period was 12 days 

 for squares falling in one day, 14 days for squares falling in 3 

 days, 14.1 days for squares falling in 5 days, 15.5 days for 

 squares falling in 7 days, 18.3 days for squares falling in 9 days, 

 18.8 days for squares falling in 11 days, 20 days for squares 

 falling in 13 days, 22 days for squares falling in 15 days, and 

 23 days for squares falling in 16 days. In August, 1906, at 

 Dallas, Texas, it was found that the period ranged from 17.9 

 days for squares falling in 7 days to 36 days for squares falling 

 in 22 days, with almost a perfect curve of increase. The fig- 

 ures for this series of observations, when considered by seasons, 

 show also the effect of the mean temperature. Squares which 

 fell in 7 days developed weevils in the latter part of June in 

 16.3 days, in the first of July in 16 days, the last part of July 

 in 16.9 days and the middle of August in 17.9 days, and this 

 variation is what might be expected from the differences in 

 the temperature. Just as striking is the series of observations 

 for squares falling in 11 days at Victoria in 1904. In June 

 these squares averaged 17 days, the first half of July 18. 8 days, 

 the last half of July 20.6 days, the first half of August 21.5 

 days, and the last of September 25.5 days. 



It may be seen from this brief discussion that it is impos- 

 sible to frame any definite law of effective temperature without 

 also including a law of effective humidity and giving due con- 

 sideration to the quality of the food supply and the amount 



