46 



Probably the greater activity of the first generation may account for 

 their somewhat shorter life. The average active life period for all 

 generations is probably not far from 71 clays for males and 64 days 

 for females. 



DURATION OF LIFE ON BOLLS ALONE. 



As weevils appear to feed freely on bolls in the field after the period 

 of maximum infestation has been reached (PL V, fig. 23), these tests 

 were made to determine whether they might be able to live normally 

 with no other food. 



A number of weevils were placed upon bolls as soon as they became 

 adult. Others which had first been fed upon squares were given bolls 

 after they had become hard and had shown themselves to be in a nor- 

 mally healthy condition. Of the total 37 weevils thus tested, 16 were 

 males and 21 were females. The males showed an average duration of 

 life of 19.7 days, while the females survived for only 15.2 days. This 

 is a much shorter period than the normal period of life upon squares 

 for either sex. There are also indications that the production of eggs 

 does not continue normally when bolls alone are accessible for food. 



DURATION OF LIFE ON COTTON LEAVES ALONE. 



To determine whether they could live upon the foliage of cotton 

 alone 69 newly transformed weevils were at the 1st of October, 1902, 

 placed upon fresh leaves, which were renewed at frequent intervals. 

 During the first three weeks 52 of these weevils (21 male and 31 female) 

 died, leaving 17 alive and well; 11 of these were then returned to 

 squares and 6 continued upon the leaves. Of these 6, 3 lived to be 

 81 days old and were then intentionally killed for dissection. The 

 average duration of life of those kept entirely upon leaves was over 

 30 days. 



In another test 310 weevils were placed upon leaves alone during 

 October, 1904. Seventy-four per cent of these died in less than 10 

 days, while 7.4 per cent lived for an average of over 3S.3 days, when 

 they were placed in hibernation. In a check experiment on 42 wee- 

 vils, 43 per cent died in less than 5 days, and 24 per cent lived for an 

 average of 36 days. As in the preceding experiment, a large propor- 

 tion died within a few days. Among those surviving the first critical 

 period, 31 per cent of those on foliage lived to an average age of 38.3 

 days, and 42 per cent of those on squares lived to an average age of 

 35.9 days. It appears, therefore, that leaves alone are very efficient in 

 sustaining life late in the fall, as well as early in the spring (see p. 54). 

 These results show clearly the ability of main' of the weevils to live 

 upon foliage alone* in the fields in which fall grazing is practiced until 

 it becomes sufficientlv cold for them to go into winter quarters (see 

 PI. VI, fig. 24). 



