LEPIDOPTEEA. 



239 



a long time. They must, in other words, kill the chrysalides, 

 to prevent the cocoons being pierced by the moth. To kill the 

 chrysalides so as to prevent the development of the imago is 

 an operation which is called the etouffage, or stifling. 



To effect this stifling, the co- 

 coons are exposed to a high tem- 

 perature. Formerly, in the Ce- 

 vennes, the cocoons were placed 

 in a baker's oven, heated for bak- 

 ing bread. But they ran the risk 

 thus of being burnt, or of a certain 

 number of chrysalides remaining 

 alive. Now, to kill the chrysalides, 

 they make use of steam at 100, 

 produced by water boiling in a 

 vessel, and which passes through 

 wicker baskets filled with cocoons. 



The rearer must also take care 

 at the time he gathers them, to 

 separate the cocoons which are 

 to provide eggs for the next year. 

 As the females are heavier than 

 the male cocoons, they easily sort 

 them with a pair of scales. 



To obtain the eggs or grain, the cocoons are fixed on sheets 

 of brown paper, covered with a slight coating of paste made 

 of flour. They are arranged in such a manner that the moths 

 shall find no obstacle when they come out of them, head fore- 

 most ; and, on the other hand, that they may be able to reach 

 with their legs the cocoon which is opposite them, so as to 

 hang on to it, and to facilitate their exit from their own cocoon 

 (Fig. 218). The meal and female cocoons are pasted on separate 

 sheets. 



It is from fifteen to twenty days after the montee or mounting, 

 and when the temperature of the rooms has been kept between 

 20 and 25, that the moths begin to be hatched. As they appear, 

 they are seized by their wings and placed on cloths stretched out 



Fig. 217. Apparatus for stifling the 

 chrysalides in the cocoons. 



