I 175 ] 34 



the end of which time the caterpillars have reached their ultimate 

 growth, are three inches in length, and of the size of a swan's quill, 

 or even lai'ger, and prepared to spin their cocoons. Each moulting take^ 

 up about two days: making, in all, about thirty-two days from the 

 hatching of the insect. 



In Pennsylvania, where artificial heat has not yet been generally 

 employed, the worms which have proceeded from stocks long among 

 us, come to maturity in about forty-two days; in Mansfield, Connec- 

 ticut, in about five weeks. The small white worms, of the same place, 

 which produce beautiful and fine white silk, and two crops annually, 

 feed twenty days. A part of the worms produced from eggs import- 

 ed in the spring of 1836, from Genoa, by the writer, and reared in the 

 Pennsylvania Hospital, came to maturity in twenty-six days. 



The length of time passed by the worm in the state of a chrysalis, 

 depends much upon the degree of heat in which the cocoons are kept. 

 If the temperature be about 66° of Fahrenheit's thermometer, the moths 

 will make their appearance after fifteen days; while, on the contrary, 

 the experienced Abbe Sauvage informs us, that he has prevented them 

 from coming forth for a month, by keeping the cocoons in a vault.* 

 This is very important information, as, by having recourse to this ex- 

 pedient, time will be given to wind off the cocoons, without baking or 

 steaming them to kill the chrysalis. 



In whichever way the cocoon is pierced, as soon as the head of the 

 moth is out, the efforts he makes to bring forward the rest of his body, 

 increase the opening; his two forward legs are soon out, and then, at- 

 taching them strongly to the exterior part of the cocoon, he uses this 

 as a new support; other legs come out, and finally the whole moth 

 escapes, leaving behind, in the cocoon, his caterpillar's skin, in a 

 crumpled state, with the hgad and jaws attached thereto, and the shell 

 of the chiysalis. Having gained their liberty, the moths discharge a, 

 red excrementitious fluid: neither of them attempts to fly: the male, 

 anxious to fulfil the destiny of his nature, goes immediately in search 

 of the female, fluttering his wings v/ith great rapidity, and having 

 found one, couples with her, continuing, for some time, to flap his 

 wings. After different intervals of time, they separate, and the male 

 soon after dies; the female crawls about, and lays from 200 to 450 

 minute eggs, and then she also dies. The eggs, when first laid, are 

 of a pale yellow color; but, in the course of eight or ten days they as- 

 sume a reddish gray hue, and, sometime after that, a pale slate coloro 

 The unimpregnated, and consequently sterile eggs, remain yelloWj 

 and are more depressed on their surface than good eggs. 



•Sar I'Education des Vers a Sole. 3d Memoir, p. 1 13. 



