42 



HIBERNATIOK OF THE COTTON BOLL WEEVIL. 



the time weevils were placed therein, the source of the weevils, and 

 the nature of the shelter. Practicall}^ one-half of the weevils used 

 were collected in Texas and sent to Keatchie for this work. The 

 sections used in this comparison received weevils between Novem- 

 ber 23 and 29. 



Table XVIII. — Favorable conditions for hibernation determined by rank in percentage 

 of weevils siirvivinxj at Keatchie, La., in 1905-6. 



Section num- 

 ber in cage. 



6 and 12. 



2 and 8. , 

 1 and 7. 



4 and 10 



5 and 11 



3 and 9. 



Nature of shelter. 



Ordinary field stalks, grass, etc 



Brush, leaves, stumps, logs; stalks standing. . . 



Same as above, but stalks removed 



Cotton seed, piled but uncovered; stalks stand' 

 ing 



Absolutely bare ground 



Cotton seed piled and covered; stalks left stand- 

 ing 



Weevils 

 put in. 



2,000 

 2, 500 

 3,300 



2,000 

 2,000 



2,000 



Weevils survived. 



Number. Per cent 



4.65 

 3.56 



2.12 



1.50 

 1.50 



Rank of 

 section. 



It is evident that ordinary field conditions where stalks are allowed 

 to stand together with the grass and leaves littered over the ground 

 are as favorable for successful hibernation as any conditions. It must 

 be admitted that the shelter conditions in the bare sections (5 and 11) 

 are not such as would occur in a field plowed in the fall because of the 

 fact that the inclosed weevils could still find shelter in the structure of 

 the cage itself. This will undoubtedly explain the survival of 1.5 per 

 cent in two sections having no rubbish on the ground. It is apparent, 

 however, that even with this advantage of cage structure over bare 

 ground, slightly more than three times this percentage of weevils sur- 

 vived where ordinary field conditions existed. Without the shelter 

 afforded by the cage this difference would undoubtedly be very much 

 greater. In 9 sections which contained rubbish, among 15,500 wee- 

 vils, 567, or 3.66 per cent, survived. The shelter may therefore be 

 held accountable for increasing the survival at least 2.1 per cent. 

 Thus upon an area where no more than 15 weevils might survive with- 

 out protection, 36 at least might be expected to survive with the pro- 

 tection. 



EFFECT OF ACCLIMATIZATION UPON SURVIVAL AND EMERGENCE. 



It has already been mentioned that about one-half of the weevils 

 used in this work were collected in Texas and one-half at Keatchie, La. 

 In order to determine whether this difference in the geographical sec- 

 tion in which the weevils developed might exert an influence upon 

 their survival and emergence the records for a number of comparable 

 sections are combined. These weevils were all placed in hibernation 

 between November 25 and 29, 1905. 



