26 



one week. Development becomes slower as the temperature falls, 

 but does not cease altogether so long as cotton can live. Even frosts 

 do not destro}^ larvte in the squares and bolls, and these may finish 

 development during warmer weather after the frost has taken place. 

 The length of the larval stage in bolls is as a rule much greater. 

 If the boll falls when small the increase is- slight, but if an infested 

 boll grows on to maturity the larval stage more than any other is much 

 extended. Special observations upon the larval stage in bolls have 

 not been made, but reckoning from the known length of the whole 

 develoj)mental period in maturing bolls we may conclude that the 

 larval stage can not be less than six or seven weeks. 



PUPAL CELLS IN BOLLS. 



As the boll approaches maturity, the full-grown larva ceases to feed 

 upon the drying and hardening tissues of seed and fiber. Its excre- 

 ment, more or less mixed with lint, becomes firml}^ compacted, and in 

 the drying which occurs the mass forms a cell of considerable firm- 

 ness, within which pupation and the subsequent transformation to 

 the adult take place (PI. Ill, fig. 20). These pupal cells frequently 

 include a portion of the hull of a seed, but the writer has never found 

 a large larva or a pupa entirely inclosed within a single cotton seed. 

 The cells described are shorter and thicker than seeds, but in general 

 appearance there is considerable resemblance between them (PI. XI, 

 fig. 44). Doubtless these cells have misled some into the statement 

 that they have found weevils in cotton seeds. 



PUPATION. 



The formation of the adult appendages has gone a good way before 

 the last larval skin is cast. The wing pads ai:)pear to be nearly half 

 their ultimate size. The formation of the legs is also distinctly marked, 

 and the old head shield aj)pears to be jiushed down upon the ventral 

 side of the thorax b}^ the gradual elongation of the forming proboscis. 

 Finall3^ the tension becomes so great that the tightly stretched skin is 

 ruptured over the vertex of the head, and it is then gradually cast off, 

 revealing the delicate white i^upa. The cast skin frequently remains 

 for some time attached to the tij^ of the abdonien. 



THE PUPA. 



When this stage is first entered tlie insect is a very delicate object 

 both in appearance and in reality. Its color is either pearly white 

 or cream. The sheaths for the adult appendages are fully formed at 

 the beginning of the stage and no subsequent changes are apparent 

 except in color (PI. I, figs. 5 and G). The eyes first become black, 

 then the proboscis, el^^tra, and femora become brownish and darker 

 than the other parts (PI. Ill, fig. 17). 



