31 



least three times, the third molt being at the formation of the pupa, 

 which after a few days sheds its skin, whereupon the transformation 

 becomes completed. These immature stages require on the average 

 between two and three weeks. A further period of feeding ecfual to 

 about one-third of the preceding developmental period is required to 

 perfect sexual maturity so that reproduction ma}^ begin. 



Variation in size depends directly upon abundance and condition of 

 the food suppl}^ Weevils of average size are about 8 mm. in length, 

 one-third as broad as long, and weigh about one-fourth of a grain. 

 Color varies as widely as does size. It is usually of a gray or yellow- 

 brown, and is most markedly yellow in the largest weevils. Sexes 

 are produced in practically equal numbers, the males predominating 

 slightly. No other food has been found which will attract weevils 

 from squares and no plant but cotton upon which they can sustain 

 themselves for any considerable length of time. (See PL II, fig. 7.) 



THE EGG. 



The egg of the boll weevil is an unfamiliar object even to many who 

 are thoroughly familiar with the succeeding stages of the insect. If 

 laid upon the exterior of either square or boll it would be fairly con- 

 spicuous on account of its pearly white color. Measurements show 

 that it is, on the average, about 0.8 mm. long by 0.5 mm. wide. Its 

 form is regularly elliptical (PI. I, fig. 3), but both form and size vary 

 somewhat. Some eggs are considerably longer and more slender than 

 the average, while others are ovoid in shape. The shape may be 

 influenced by var3dng conditions of pressure in deposition and the 

 shape of the cavity in which it is placed. The soft and delicate mem- 

 brane forming the outer covering of the egg shows no noticeable 

 markings, but is quite tough and allows a considerable change in form. 

 Were the eggs deposited externally they would doubtless prove 

 attractive to some egg parasite as well as to many predatory insect 

 enemies. Furthermore, the density of the membranes would be 

 insufficient to protect the egg from rapid drying or the effects of 

 sudden changes in temperature. All these dangers the female weevil 

 avoids by placing the eggs deeply within the tissue of the squares or 

 bolls upon which she feeds. As a rule, the cavities which receive eggs 

 are especiall}^ prepared therefor and not primaril}^ for obtaining food. 

 Buried among the immature anthers of a square or on the inner side 

 of one carpel of a boll, as they usually are, weevil eggs become very 

 inconspicuous objects (PI. Ill, fig. 8) and are found only after careful 

 search. 



EMBRYONIC DEVELOPMENT. 



Owing to the transparency of the egg membranes, something of the 

 development of the embryo can be seen through them. Special study 

 is now being made of the embryology of the weevil. The fully devel- 



