L12 



THE MEXICAN < OTTON-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 <an see the force of Table XLYI. It is even more evident 

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



Tabj i XLVII. 



Number of boll u<> vils in each 1,000 which would have survived 

 destruction of stalks on a given date. 



Date of destruction. 



In Texas. 



In Loui- 

 siana. 



September 16-30 



2 



23 

 56 

 1.54 

 160 

 (?) 

 (?) 



3 



Ootober 1-15 



20 



L6-31 



hO 





88 





60 





106 





126 







DELATION 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. 



Place. 



Date installed. 



Weevils. 



Shelter. 



Survival. 





October 26 



do 



2,436 

 2.158 

 2.375 

 2,850 

 2,850 



Average 



Percent. 



20.00 





37. 76 







October 28 



November fi. . . 

 November 10. . 



Average 



5. til 



Do 



23. 65 



Do 



Average 



12.70 







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. 





Description. 



Number 

 weevils. 



Per cent 

 of sur- 

 vival. 



Periods of emer- 

 gence. 



Rainfall and icmpera- 

 ture, Oct. 1-Mar. 15. 



Qd year. 



Rain- 

 fall. 



Abso- 

 lute 

 mini- 

 mum. 



Total 



degrees 



below 



32. 



Tallulah, La.. 

 1910-11. 



Tex.. 

 Tallulah, La., 



' 10. 



10 cages, variety of 

 shelter, installed 



15 Per. 1. 



shelter, Sept." 21- 

 L8. 

 .great variety 



of shelter, Sept. 16- 

 Dec. 11. 



8, 139 

 12,087 

 21,835 



0.5 



.9 



1.4 



Feb. 15-June 4 . . . 

 Feb. 19- June 16 . . 

 Feb. 15-June 27 . . 



Inches. 

 8.30 



22.61 



19.34 



°F. 

 9.5 



15.0 



13.0 



°F. 

 199.5 



233.0 



378.5 



