36 



THE MEXICAN COTTON-BOLL WEEVIL. 



with them, to be of entirely different species. So far as dimensions 

 may convey an idea of the size, we may say that the weevils range 

 from 2.5 mm. to 6.75 mm. (fa to £ inch) in length, measuring from 

 base of beak to apex of elytra, and from 1 mm. to 3 mm. (fa to | 

 inch) in breadth at the middle of the body. 



WEIGHT OF WEEVILS. 



A number of interesting observations have been made at various 

 times upon the weight of weevils in connection with the nature of the 

 food supply. These observations have been tabulated, as follows: 



Table VII. — Weight of boll weevils from different sources. 



COLOR OF WEEVIL. 



Color is very often a variable character in insects, and the boll 

 weevil presents considerable range in this respect. Normally, the 

 general color becomes darker with age. Consequently, hibernated 

 weevils are the darkest found, but another factor must be considered. 

 As has been noted, whatever influences the size of the larva affects 

 directly the size of the adult, and it is noticeable that weevils of the 

 same size are also, as a rule, similar in color. In general, the smaller 

 the size of the weevil, the darker brown is its color; the largest weevils 

 are light yellowish brown. Between these two extremes are the 

 majority of average-sized weevils, which are either of a gray-brown 

 or dark yellow-brown color. In the opinion of Dr. W. E. Hinds 

 the principal reason for the variation in color lies in the degree of 

 development of the minute, hair-like scales, which are much more 

 prominently developed in the large than in the small specimens, 

 although the color of old specimens is often changed by the abrasion 

 of the scales. These scales are yellow in color, while the ground 

 color of the chitin bearing them is a dark brown or reddish 

 brown. The development of the scales appears to take place mostly 

 after the adult weevils have become quite dark in color, but before 

 the chitin becomes fully hardened. They seem, therefore, to be, to 

 a certain extent, an aftergrowth which depends upon the surplus 

 food supply remaining after the development of the essential parts 

 of the weevil structure. 



