30 



PAPERS OX THE COTTON BOLL WEEVIL,, ETC. 



not fall for about 10 days and remains green long after the hatching 

 of the egg, which takes place in about 2.5 days, there seems no reason 

 to suspect any considerable mortality at this period. After the infested 

 squares have dried or decayed it becomes very difficult to find any 

 trace of larvae which die before they are half or two-thirds grown. 

 The table shows that in about 63 per cent of the infested squares no 

 trace of weevil stage could be found. In this percentage are the 

 squares which had received feeding punctures onl} T and a large num- 

 ber showing external signs of egg punctures, thus, indicating that a 

 great mortality occurs while the larvae are less than half grown. Fur- 

 thermore, it will be observed that of those individuals which pass the 

 larval stage succesfully 1.6 per cent died in the squares or while emerg- 

 ing. It has previously been shown that only about 1 per cent of 

 squares placed where fully exposed to sunshine developed weevils. 

 It would therefore appear that the mortality was largely due to the 

 squares becoming so dried that the food supply was cut off from the 

 3 T oung larva. Hence, it would seem that the sooner the square falls 

 after being punctured, the higher will be the mortality, provided the 

 ground is not shaded by close rows, and that any means for knocking 

 off the squares before they would naturally fall, or a variety or strain 

 of cotton which sheds its squares more quickly after being punctured, 

 will beof decided advantage in increasing the mortality of the weevil. 

 This seems to be even more marked where the squares are covered by 

 the soil as is shown in Table VI. 



Table VI. — Percentage of mortality of weevils in squares buried in soil. 





Date. 



Depth 

 buried. 



Condition. 



03 

 O 



c3 



a* 



CD 



"o 



M 



<y 



B 



Per cent dead. 



Per cent 

 alive. 



*2<d . 



£a 



o 



o 



■a 



o 



^ >. 



r. — 



aj 

 3 

 u> 



- 





T. 



- 

 > 



"z 



- 



1 



c 



88 

 > 



3 



p. 



r. 



~ 

 zr 



= 



- 



S3 



r- 

 ir. 



| 



'o 



en 



a 



- 



40 



1 



Aug 15 



(in 



h inch 



Kept moist in laboratory. 

 do 



a 25 

 a 25 



a 25 

















2 























46 



3 do 





...do... 























R? 



4 Aug. 29 



5 fin 





...do... 



7- 1 



1 

 "*2 







4 

 12 











24 

 38 



•>o 



1| inches.. 

 1\ inches.. 

 2^ inches.. 



do ... 



a 25 28 



1 



... 



44 



76 



&88 









16 



f, 



Sept. 21 



do 



Sept. 11 



do 



Sept 18 



In field .. 



50 74 

 78 7S 



8 

 4 







8 



7 





4 



9 







1 



... 



f> 



s 



do 



200 

 180 





MOO 









^ 



On surface 



r1n 





85 



15 

 26 



















 







P, 



do ... 



174 62 

 -100 91 

 401) 94. 5 

 400 81 

 400 92. 5 



12 



















c 



Juivi.'O'.toi do.... 



Under screen 















9 



q 









3 



lit 

 5 

 3 













"5 



10 



rin 





...do 



















9 



11 do 



12 rlf> 





...do 

















9 5 







400 PS 









0.5 











1 5 































a Contained larvae or pupae when buried. 

 bDead weevils eaten by ants; squares green. 

 c Ants' nest just beneath. 



