462 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1925 



without the escaj^e of the butterflies beini); thereby prevented. The 

 larger hirvae require three to four days after taking up their molt- 

 ing position to crawl out of their old skins, which become a little 

 darker and finally split downwards under the front edge and right 

 and left along the rim. The old skin retains its shape above and, 

 being relieved of its occupant, regains its former color, so that, 

 viewed casually, it is difficult to believe that it is an empty shell, so 

 closely does it resemble a real larva. 



In changing to the pupa the larval skin is not cast off, but changes 

 its shape and becomes a comparatively strong outer covering. 

 The insect shrinks away from this and becomes detached, so that 

 it can be shaken like a nut in its shell. The true pupal skin is very 

 thin and transparent and, provided, of course, the outer shell is 

 opened, the color changes of the chrysalis can be observed plainly. 

 After the larva has taken up its position for the transformation 

 there is no change for 36 hours or so, the first being a narrowing of 

 the thoracic portion with an increased thickness of the same. Upon 

 examining the future pupa at this time underneath it will be noticed 

 that the shell has closed in on each side enveloping the head and legs 

 completely; no closing in upon the prologs occurs. For some hours 

 no further alteration takes place; then the remaining portion of the 

 creature contracts, accompanied by a considerable rise in the dorsal 

 surface, the pupal change, so far as can be ascertained from external 

 observation, now being complete. For several days after the shell 

 is liable to split at the outside edge or rim if care in handling it is 

 not taken, the whole of the top being liable to split and come off like 

 a lid, and the chrysalis, being particularly delicate and pulpy, may 

 be killed. 



The perfect insect emerges in from 21 to 25 days, and further 

 astonishing developments in the life history of this strange insect 

 occur. Before bursting the outer shell the butterfly can be heard 

 moving within, and shortly a sharp, cracking sound announces that 

 the burst has been effected. Then either a portion of the shell, which 

 opens in the center in front up to the first furrow, is broken right 

 out or it opens sufficiently above after breaking away at the rim to 

 admit of the imago's emergence. 



Instead of the weak drooping wings of a butterfly the creature 

 that emerges has little short appendages like those of a freshly 

 emerged moth, and lying very flat; the front wing is creamy white 

 to the extreme tip, and the edge of the hind wing projects from 

 under this ever so little. The abdomen looks very large, a thick 

 mass of furry looking substance showing on each side of it to the 

 tip. On the thorax small tufts of loose, brownish scales may be 

 noted which easily roll off. 



