10 BULLETIN 926, U. S. DEPARTMENT OF AGRICULTURE. 



was made by a first-generation female weevil that became adult dur- 

 ing the latter part of June. This weevil lived a total of 67 days. 

 The maximum length of life for the male weevils was also recorded 

 for a first-generation weevil that became adult during the latter part 

 of June. This weevil lived a total of 65 days. The average lon- 

 gevity for hibernated weevils fed with sea-island cotton plantlets was 

 11.05 days. The weevils lived 10.7 days on sea-island squares and 

 15.3 days on green sea-island cotton bolls. By comparing the aver- 

 age longevity of the weevil on sea-island cotton with the average 

 longevity on upland cotton, it is clearly demonstrated that there is 

 little, if any, difference in the food value of sea-island and upland 

 cotton on the longevity of adult weevils. 



THE SIZE OF THE COTTON SQUARE ATTACKED BY BOLL 



WEEVILS. 



Male and female weevils feed largely on the cotton squares, except 

 in the case of sea-island cotton, where there is a decided tendency 



to feed upon the bolls as well as the 

 squares. Upland cotton squares grow 

 very rapidly and there is little oppor- 



#^^k /'I Wk tunity afforded for direct feeding on 



fc* 'it% wt ' ^ e ver y sma ^ squares, except during 



^7 W the period when the first squares come 



on the plants and again when all 

 fig. 2.— Three sizes of sea-isiand cot- squares are punctured. However, 

 ton squares chosen for oviposition by sea-island squares do not grow very 



the boll weevil. . ,. , . . , . 



rapidly and a large number ol the 

 small squares are shed by the plant from feeding and egg punctures. 

 It has been observed that a large number of undersized weevils are 

 produced in sea-island cotton fields. These weevils are largely the 

 result of eggs having been deposited in undersized squares, which re- 

 sulted in an undersized weevil, owing to the lack of proper larval food 

 (fig. 2). When a large number of sea-island squares are offered a 

 female it has been observed that she invariably chooses the smaller 

 squares for oviposition purposes. No records are available to show the 

 length of the developmental period for weevils developing in under- 

 sized squares on sea-island cotton ; however, it is not thought that there 

 is much variation from that in large-sized squares. Observations on 

 the size of weevils bred from bolls show that, except in the case of 

 very young bolls which shrivel and dry very rapidly, nearly all 

 weevils produced are of normal size. Sea-island cotton bolls seldom 

 produce small-sized weevils, as the boll is very moist and furnishes 

 much better conditions for weevil development than upland cot- 

 ton bolls. 



