ORDER IV.—MOTHS AND BUTTERFLIES. 157 
wide, which is fastened securely to the twigs, and which is 
so strong that its outer 
coat can not be torn 
with the fingers. The 
inside of this outer 
skin or covering is 
thickly lined with soft 
but strong brown silk, 
which may be woven 
and unwound like that 
of any Silk-worm, and 
surrounds a_ black, 
shining chrysalis, from 
which in due time the 
Moth issues. 
Fig. 33 represents 
the cocoon, and Fig. 
34 its silk. 
These cocoons re- 
main motionless on the 
bushes until May or 
June, and though oft- 
en exposed in the open 
air to a temperature as 
low as 10° Fahr. they 
are perfectly protect- 
ed. Those which we 

Figure 933. \ 
Cocoon of the Cecropia. 
have raised in the house come out as early as April, be- 
cause the warmth of the room develops them sooner. When 
ready to emerge from its shell, the Moth throws out a caus- 
tic liquid from its mouth, which destroys the fibres of silk 
and enables it easily to pierce the upper end of its parch- 
ment-like prison, from which it then creeps out with short, 
damp antenne and wings, which by continual moving be- 
come dry and enlarged to their natural size. 
