34 THE MEXICAN COTTON-BOLL WEEVIL. 



the dark color of the body contents, which show through the thinner, 

 almost transparent portions of the body wall. The dorsum is strongly 

 wrinkled or corrugated, while the venter is quite smooth. The 

 ridges on the dorsum appear to be formed largely of fatty tissue. 

 After becoming full grown the larva ceases to feed, the alimentary 

 canal becomes emptied, and both the color and form of the larva are 

 slightly changed. The dark color disappears from the interior and 

 is replaced by a creamy tint from the transforming tissues within. 

 The ventral area becomes flattened, and the general curve of the 

 body is less marked. Swellings may be seen on the sides of the 

 thoracic region, and when these are very noticeable pupation will 

 soon take place. 



THE PUPA. 1 

 (PI. Ill, h, i,j.) 



When the pupal stage is first entered the insect is a very delicate 

 object both in appearance and in reality. Its color is either pearly or 

 creamy white. The sheaths for the adult appendages are fully 

 formed at the beginning of the stage, and no subsequent changes are 

 apparent except in color. The eyes first become black, then the 

 proboscis, elytra, and femora become brownish and darker than the 

 other parts. The pupa of the boll weevil can be distinguished 

 readily from any other pupa which might be found in a cotton 

 square or boll. Like all other curculionid pupa 1 , its beak rests on 

 the venter of the body, with the legs drawn up at the sides and with 

 the elytra on the dorsum as they will appear in the adult. But the 

 boll-weevil pupa has two large quadrate tubercles on the prothorax, 

 practically at the anterior apex of the body, and the abdominal 

 segment which serves as the apex is produced in a rather chitinous 

 flattened process, which is inflated at the middle and deeply quad- 

 rately emarginate at apex, leaving only two strong acute teeth 

 projecting. 



The final molt requires about 30 minutes. The skin splits open 

 over the front of the head and slips down along the proboscis and 

 back over the prothorax. The skin clings to the antennas and the tip 

 of the proboscis until after the dorsum has been uncovered and the 

 legs kicked free. Then by violently pulling upon the skin with the 

 forelegs the weevil frees first the tip of the snout and then the anten- 

 na?, and finally with the hind legs it kicks the shrunken and crumpled 

 old skin off the tip of the abdomen. 



THE ADULT. 



(PI. II, a; PI. Ill, d,f,g.) 

 BEFORE EMERGENCE. 



Immediately after its transformation from the pupa the adult is 

 very light in color and comparatively soft and helpless. The proboscis 

 is darkest in color, being of a yellowish brown ; the pronotum, tibiae, 

 and tips of the elytra come next in depth of coloring. The elytra are 

 pale yellowish, as are also the femora. The mouth parts, claws, and 



1 Modified and expanded from Bulletin 51, Bureau of Entomology, p. 38. 



