30 



darkening of the ground color makes the scales more apparent, and 

 thus gives the impression of further development after emergence has 

 taken place. 



SIZE OF WEEVILS. 



Size of boll weevils is an especially variable quantity, and, as usual, 

 varies almost directly in proportion to the abundance of the larval 

 food supply and the length of the period of larval development. The 

 extremes are so great that the smallest and largest weevils would be 

 thought by one not thoroughly familiar 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 3 to 8 mm. (-J to ^ inch) 

 in length, including the proboscis extended, and from 1 to 3 mm. ( ¥ ^ 

 to ■£ inch) in breadth at the middle of the body. (See PL I, fig. 1.) 



RELATION OF SIZE TO FOOD SUPPLY. 



The smallest weevils are developed from squares which were very 

 small, and which, for some reason, either of plant condition or of 

 additional weevil injury, fell very soon after the egg was deposited. 

 The supply of food was not only small, but, owing to the immaturity 

 of the pollen sacs, its quality was also poor. Normally squares con- 

 tinue to grow for a week or more after eggs are deposited in them, and 

 such squares produce the weevils of average size and color. 



The largest weevils are produced in bolls which grow to maturity. 

 In them the food supply is most abundant, and the period of larval 

 development is several times as long as it is in squares. Possibly 

 these differences in size may be better shown by a summary of 

 observations which were made upon the weight of adults. 



WEIGHT OF ADULTS. 



The weevils used in these experiments were bred to insure their 

 coming from the proper source. After emergence they were fed for 

 some time to bring them up to their normal weight. 



Table V. — Summary of weight of weevils. 



Source of weevils. 



Bred from picked small squares . . 

 Bred from average fallen squares 

 Bred from large bolls 



Total _. 



Average weight per weevil, all sources 



Number. 



162 



Average 

 weight. 



Grain. 

 0.105 

 .231 



.825 

 .227 



It should be noted that these figures do not nearly represent the 

 weight of the extremes in size, but they do indicate the difference in 

 the average weevil of each class. 



