LEPIDOPTERA. 239 
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 étouffage, or stifling. 
To effect this stifling, the cocoons are exposed to a high tem- 
perature. Formerly, in the Cé- 
~-vennes, the cocoons were placed in 
a baker’s oven, heated for baking 
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 co- 
coons. 
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 female cocoons are heavier 
than the male cocoons, they are - Vl ] 
easily separated by weighing Fig. 217.—Apparatus for s‘ifling the 
. ° chrysalides in the cocoons. 
them in 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, moreover, so 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 male and female cocoons are pasted on separate sheets. 
It is from fifteen to twenty days after the montée, 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 the wings and placed on cloths stretched out 

