78 THE MEXICAN COTTOX-BOLL WEEVIL. 



Additional illustrations are furnished in Table XXX. 

 Table XXX. -Observations upon infestation by tht bollweevil, various localities, 1904* 1 





- 



, 







- 









<- IM 









| 





a 



°| 



~ . 



o 9 



- 



t - — 



o 





a 



si 



g ■ - 



E 



1 § 





3 



y 

 I 



|| 



n 



* 3 



? 5f 



3 □ 





ev: E'r: 



& . 



~ % 



Locality (Texas). 



!l 



— - 

 E 



s 



a 



■_ 



- 

 S 



3 



e 



33 

 O 



O 



3 



c8 



1 y . 



? 1 7 - 

 - — ■- 



o — 



I 



> DO P 



ital Qumbe 

 hoi is exai 



i-1 f '- J ' ~ 



~ S . £ ,0 



r - - £ £ M 



> ~ — > B-S 



03 





14 



' 



- 



H 





H 



<j 



E- 



" « 



- 









1904. 



















Calvert 



12 



2 



Aug. 23 to 



2.754 



94.0 



251 



9.1 



1.175 



'.14. 7 



1.8 



4.2 



Corsicana: 







Sept 9. 



















A 



12 





Julv 29 to 



6.951 



72.4 



376 





2,506 



71.9 



.6 



27 









Sept. 12. 

















B 



11 





Julv 28 to 

 Sept. 12. 



4 534 



80.4 



407 



9.0 



3,261 



64.9 



.6 



19 

























15 





July 30 to 

 Sept, 13. 



6 445 



64.4 



317 



5.0 



4,618 



64.9 



1 ° 



34 5 























Palestine 



22 



2 



Aug. 26 to 



3,719 



91.3 



274 



7.4 



2,456 



92.8 



7 



8.2 









Sept. 14. 















\ ictoria 



11 



18 



June 18 to 



13,227 



54.2 



170 



1.3 



544 



66.9 



6.1 



44.6 









Sept. 24. 



















"W harton 



4 



4 



July 22 to 

 Aug. 25. 



June 18 to 

 Sept. 24. 



5,005 



65.0 



167 



3.3 



230 



46.4 



10.2 



25 3 

























Total 



87 





42,635 





1.962 





14.790 



















6 







70.1 





4.6 





80.0 



2.2 



27.7 











i From Bull. 51, Bureau of Entomology, p. 116. 



Prof. Sanderson 1 has estimated that usually 50 per cent of the 

 squares will be punctured by about two months after the cotton com- 

 mences to square, at which time there would normally be about 100 

 squares to the stalk. When one-half of the squares are punctured it 

 may be readily concluded that there are probably sufficient weevils 

 present to prevent any more squares from forming fruit. It will be 

 seen, therefore, that the critical period in the relation between natural 

 increase of squares on the plant and increased injury by the boll 

 weevil is during the period of six to eight weeks after the first squar- 

 ing, which usually coincides more or less closely with the time between 

 the appearance of the second and third broods of the weevils. Thus, 

 if we consider six weeks as the average time for cotton to begin to 

 square after planting, it will be seen that the bulk of the fruit must 

 be set in 85 or 95 days after planting. In other words, to escape 

 injury by the boll weevil, cotton must be so grown that the bolls will 

 commence to open in about 100 days after planting and that all the 

 fruit which will probably be secured must be set within 45 days after 

 the squares begin to form. The advantage of early planted cotton 

 and rapid-maturing varieties becomes, therefore, very apparent. 



Field examinations have shown that the period of maximum infes- 

 tation is reached between August 1 and 20, and that from 6,000 to 

 10,000 adult weevils per acre is sufficient to cause maximum infesta- 

 tion within a few days. The highest number of weevils per acre which 

 has ever actually been recorded from a locality 



during the summer was 



Bull. 63, Bureau of Entomology, p. 38. 



