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ing leaves it covered with a fine wbite dust. This secretion is supposed 

 to correspond to the urine of higher animals. 



At this time the caterpillar skin is cast for the last time. The head 

 splits through the middle, the split extending down the back, and by 

 repeated vermicular movements the creature forces the skin backward 

 until it remains a conical button packed at the bottom of the cocoon. 

 The pupa is at first a soft sticky thing, with rudimentary members simi- 

 lar to those of the fully- developed moth, excepting the wings and sex- 

 ual organs, which are little developed. In a short time all of these 

 structures become agglutinated together by drying, and although their 

 outlines are still discernible, they can no longer be separated. 



The pupal period is forty days. 



Let us consider the mercantile value of the structure which this in- 

 sect has made for its own protection. If the cocoon be placed in hot 

 water and stirred about, various ends of the fiber which was broken in 

 stripping off the leaves will be found floating. If these are caught upon 

 some rough substance and drawn out of the water, they will unravel 

 from the cocoon and soon end. By perseverance a fiber will be found 

 which unravels indefinitely. In the practical application of this fact 

 for the reeling of silk several cocoons are placed in the water together 

 and their fibers joined to form a single thread. 



The peculiarities of this silk are that the fiber is strong and loosely 

 laid, therefore comparatively easy to reel, but it is coarser than the 

 Bomhyx mori silk and does not take a dye readily. The silks of the 

 various American species are somewhat finer, of various shades of brown, 

 and difficult to reel because of the compactness of the cocoon and the 

 delicacy" of the thread. I have, however, specimens of the Cecropia 

 silk which was of such quality that it could be manipulated. 



In gathering cocoons for silk they should be taken while fresh, as 

 soon as the worm has completed its pupal change and before the weather 

 has affected the quality of the fiber. The pupa may be killed by steam- 

 ing and drying. The cocoons can then be packed and i^reserved for 

 reeling. The Japanese prepare the yama-mai by killing them in the sun 

 or baking them in ovens. 



The first change occurs at about the fifth week after the spinning; 

 the chrysalis skin bursts, and the moth emerges by emptying a fluid 

 which softens the fiber and then breaking its way through the end of 

 the cocoon. After about an hour the wings become expanded and the 

 perfect insect is before us. The female is slightly larger than the male 

 and of a more somber color. The males vary in tint from dark choco- 

 late to bright yellow, while the female varies from brown to orange. 

 The forewings are strongly curved along the costal margin and acutely 

 angled at the tip. Each wing presents a transparent eye-like spot, in 

 this respect resembling the Polyphemus and Luna. The vivid coloring 

 and strongly- marked difl'erence between the male and female serve to 

 distinguish this species from A. pernyij its Chinese congener. 



