20 



LIFE HISTORY. 



SUMMARY. 



The egg is deposited by the female weevil in a cavity formed by eat- 

 ing into a square or boll. The egg hatches in a few days and the 

 footless grub begins to feed, making a larger place for itself as it 

 grows. During the course of its growth the larva sheds its skin at 

 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 equal to 

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

 perfect sexual maturity so that reproduction may begin. 



Variation in size depends directly upon abundance and condition 

 of the food supply . 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 PI. II, fig. 12. 



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 

 conspicuous 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. Ill, fig. 14), 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 varying conditions of pressure in deposition 

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

 cate membrane forming the outer covering of the egg shows no notice- 

 able 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 predator} 7 

 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 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 especially prepared therefor and not primarily for obtaining food. 

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

 one carpel of a boll, as the3 T usualty are, weevil eggs become ver} r incon- 

 spicuous objects (PI. I, fig. 3) and are found only after careful search. 





