HIBERNATION. 



107 



time of emergence varies with the total effective temperature and 

 the rainfall. Computing the total effective temperature from Jan- 

 uary 1 in daily units of mean temperature above the mean of 56° F. 

 (average zero of effective temperature) it is found that approximately 

 172.6° F. of effective temperature and 5.1 inches of rain are necessary to 

 bring the weevils out of hibernation in comparatively large numbers. 

 If the rainfall is greater than 5.1 inches the necessary effective 



S 6 7 



9S* 



/20» /45° /70° /95° 220° 245" 



295" 



Fig. 23. 



-Diagram illustrating relations of effective temperature and precipitation to date of beginning 

 emergence of the boll weevil. (Original.) 



temperature usually will be less than 172.6° F., and, on the other hand, 

 if the total effective temperature is greater than 172.6° F. the necessary 

 rainfall will usually be less than 5.1 inches. This may be seen by 

 reference to Table XLI and by the diagram (fig. 23). Dis- 

 crepancies wdl occur with regard to this formula and will in a large 

 measure be due to the type of shelter or to great irregularities in the 

 climate. 



Table XLI. — Relation of effective temperature and precipitation to date of beginning 

 emergence of the boll weevil. 



Place. 



Tallulah.,1910 

 Mansura, 1910 

 Dallas, 1908... 

 Dallas, 1907... 

 Mansura, 1909 

 Victoria, 1907. 

 Calvert, 1907.. 



Total 

 effective 

 tempera- 

 ture from 



Jan. 1. 



F. 

 65 

 115 

 160 

 170 

 185.5 

 260 

 303.7 



Total 

 precipita- 

 tion from 



Jan. 1. 



Inches. 



10.5 

 7.3 

 6.5 

 2.2 

 5.5 

 1.3 

 2.35 



Date of 



first 



extensive 



emergence. 



March 1. 

 March 2. 

 March 12. 

 March 3. 

 February 21. 

 February 23. 

 March 5. 



