THE CANADIAN ENTOMOLOaiST. 25 



to the cocoons of the Bombycidne. The cocoon made by the Worm of 

 the Orient has, from the circumstance that its silk is so extensively used 

 in manufacture, been fully described. 'I'his paper concerns those of the 

 Polyphemus, Cecropia, Cynthia, Luna and Promcthea caterpillars, and it 

 may be regarded as an endeavor to foster an organized system of silk 

 culture with these worms, the Cynthia worm especially favoring cultivation, 

 as it is double brooded, and since its introduction from the East, together 

 with its food plant, the Ailanthus, it has become largely distributed 

 throughout the country. The habitat of some of these species is co- 

 extensive with the Union, and silk culturers are alike advantaged in every 

 section of the country with an abundance of food plant in our native 

 trees. The silk produced by them, though not of as fine a texture as that 

 spun by the Mori Worm, is yet abundant and of much greater strength. 

 Notwithstanding the fact that the pointed end of the cocoons of the 

 Cecropia, Cynthia and Promethea worms is left open for the exit of the 

 moth, the threads are unbroken and the cocoons can be unwound. The 

 Mori Worm covers the interior lining of the cocoon with a gummy secre- 

 tion, and when the moth escapes, the threads, if not broken, are thought 

 to be in such danger that cultivators of silk destroy the pupa before the 

 period of emergence. There are Entomologists, however, who deny that 

 the threads are broken at all, for they admit having succeeded in unwind- 

 ing cocoons from which the moths have escaped. The Cecropia, Cynthia 

 and Promethea worms line each layer of silk, as well as the interior of the 

 cocoon, with a gummy secretion, leaving the silk at the exit opening free 

 of agglutinating properties. This allows of a ready escape of the imago 

 without danger to the_ thread. If the cocoons of these worms be divided 

 lengthwise, and immersed in boiling water for a few seconds, a careful 

 manipulation will permit the separation of the several layers of silk, when, 

 by the aid of a lens, the life work of the caterpillar is beautifully presented 

 and the continuity of the thread can be discovered. The exterior section 

 of the cocoons of the Cecropia and Cynthia worms can be easily divided 

 into three layers of silk, while the interior portion is divisible into six. 

 The Luna and Polyphemus worms construct cocoons somewhat similar to 

 the Mori Worm, and as all parts of the interior lining are sealed, it 

 becomes prudent, perhaps necessary, to destroy the pupa. 



