112 



THE MEXICAN COTTON-BOLL WEEVIL. 



Converted into terms of the number of weevils in every thousand 

 which would survive the winter if stalks were destroyed on a given 

 date, we can see the force of Table XLVL It is even more evident 

 from the arrangement of the data given below in Table XLVII. 



Table XLVII. — Number of boll weevils in each 1,000 which would have survived 

 destruction of stalks on a given date. 



Date of destruction. 



In Loui- 

 siana. 



September 16-30 



October 1-15 



October 1(5-31... 

 November 1-15.. 

 November 16-30. 

 December 1-15. . 

 December 16-31. 



RELATION OF SHELTER TO SURVIVAL. 



It has already been stated that the density of the shelter has a 

 bearing upon the survival. This is best shown by the following 

 records (Table XLVIII) : 



Table XLVIII. — Relation of shelter of boll weevils to their survival. 



RELATION OF CLIMATE TO SURVIVAL. 



Another important consideration in determining the causes for 

 high or low survival is the climate. Some of the principal relation- 

 ships are brought out in Table XLIX below: 



Table XLIX. — Relation of climate to survival of boll weevils in hibernation. 



Place and year. 



Tallulah, La., 

 1910-11. 



Dallas, Tex., 

 1907-8. 



Tallulah, La., 

 1909-10. 



Descript ion. 



10 cages, variety of 

 shelter, installed 

 Oct. 15-Dec. 1. 



9 cages, variety of 

 shelter, Sept. 21- 

 Nov. 18. 



19 cages, great variety 

 of shelter, Sept. 16- 

 Dec. 14. 



Number 



of 

 weevils. 



8,439 

 12,087 

 21,835 



Per cent 

 of sur- 

 vival. 



0.5 



.9 



1.4 



Periods of emer- 

 gence. 



Feb. 15-June 4 . . 

 Feb. 19-June 16 . 

 Feb. 15-June 27 . 



Rainfall and tempera- 

 ture, Oct. 1-Mar. 15. 



Rain- 

 fall. 



Inches. 

 8.30 



22.61 

 19.34 



Abso- 

 lute 

 mini- 

 mum. 



'F. 



9.5 



15.0 

 13.0 



Total 



degrees 



below 



32. 



°F. 

 199.5 



233.0 

 378.5 



