44 



primary characters, thus requiring a certain amount of dissection in 

 each case. Such determinations have been made upon large numbers 

 of weevils taken in the tield and upon many bred in the laboratory at 

 various seasons of the year. The results are briefly summarized in 

 Table VIII: 



Table VIII. — Proportions of the sexes. 





Number 



of 

 males. 



Number 



of 

 females. 





240 



269 



43 



45 



52 



201 



599 



260 



Hibernated weevils, 1902-3 



174 





32 



Bred weevils, 1903 



33 



Field weevils, midsummer, 1903 



59 



Weevils taken in hibernation, January to March, 1904 



159 



Weevils collected before hibernation, 1903, and after emergence from hiberna- 

 tion, 1904 



338 







Total 



1,449 



1,055 







From these 2,504 determinations it appears that males are some- 

 what more numerous than females, the percentage being nearly 58 of 

 males to 42 of females. It is noticeable, however, that the only 

 season at which a preponderance of males occurs is during late fall. 

 If we exclude the figures for hibernated weevils for a moment, we find 

 that the totals for the balance of the season are remarkably close for 

 the two sexes, being 380 males and 384 females. It seems safe to say, 

 therefore, that the sexes are practically equal in numbers except that 

 more males than females seem to be found among hibernating weevils. 

 It has been shown by breeding experiments conducted at low tempera- 

 tures that the retardation of development, such as is due to approach- 

 ing cold weather, favors the development of males. Not only was 

 there a larger number of males than of females taken in December, 

 1902, but there were also more males than females taken in the field in 

 the spring of 1903 among the hibernated weevils which lived through 

 the winter. According to the determinations made, 64 per cent of the 

 259 weevils dying during the winter were males and 56 per cent of the 

 weevils living through the winter were also males. Considering only 

 weevils taken during or near hibernation time, it seems that during 

 that period over 61 per cent are males and 39 per cent are females. 

 Since it appears that females require fertilization in the spring before 

 they begin to deposit eggs, the preponderance of males at that time 

 acts as a provision to insure the propagation of the species. 



DURATION OF LIFE UPON SQUARES. 



The observations made along this line may be divided into eight 

 groups, each dealing with some special food condition or class of 

 weevils. For the confinement of weevils in the laboratory the most 

 satisfactory apparatus tried, both for convenience in handling and for 



