43 



opment the scales are largely produced and give the strong yellow 

 tone to the color which is characteristic of them. 



The development of the scales appears to take place mostly after 

 the adult weevil has become quite dark in color but before it becomes 

 fully hardened. The} T seem, therefore, to be a sort of nonessential 

 aftergrowth which depends upon the surplus food supply remaining 

 after the development of the essential parts of the weevil structure. 



SIZE AND COLOR NOT INDICATIVE OF SEX. 



Eminent coleopterists have studied the boll weevil most carefully 

 with the purpose of discovering some external character by which the 

 sexes could be distinguished, but all have failed to find any reliable 

 points of distinction. The writer therefore does not hesitate to own 

 that he also has failed to find any reliable character for the distinction 

 of the sexes. Many persons have the idea that the small dark weevils 

 are males and the larger and lighter-colored brownish^ellow weevils 

 are females. This idea is a mistaken one. In general it is probably 

 true that the males are slightty smaller than the females, but judging 

 from determinations of the sex of many hundreds of weevils, it may 

 be stated positively that size and color are characters which are 

 related to food supply and length of the period of development and 

 are not indications of sex. The sexes seem to be about equally rep- 

 resented among* the smallest as well as the largest weevils. 



SECONDARY SEXUAL CHARACTERS. 



Characters commonly used to separate the sexes in the family Cur-, 

 culionidse are not always distinctive in this species. As a rule the 

 antennae are inserted nearer the tip of the snout in the male than in 

 the female. This character is variable among boll weevils; and though 

 a large number of accurate measurements might show that a slight 

 difference generally exists, it is too inconspicuous a character to be of 

 general use. Yv 7 ith most species the top of the rostrum of the male is 

 rougher than is that of the female. However it may be with other 

 ;| species, there is but little if any difference in this respect between the 

 young adults of the boll weevil. As the individuals become older 

 the greater activity of the females serves to wear the roughness from 

 the top of the rostrum, and thus gradually, as a result of different 

 habits, this character becomes more distinctive. In less than half of 

 the. boll weevils, however, is this character sufficiently noticeable to 

 separate the sexes. The terminal segment of the abdomen shows no 

 external difference in either sex, although in many weevils important 

 characters are there found. 



PROPORTIONS OF THE SEXES. 



No reliable secondary sexual characters having as- yet been discov- 

 ered, the certain determination of sex therefore rests solely upon the 



