84 NATURAL HISTORY. [CH. IV. 



it is influenced by the temperature of the climate in 

 which this metamorphosis is about to take place, 

 viz., in England it requires thirty days, in France 

 twenty-one, in Spain and Italy eighteen to twenty, 

 and in India only eleven days. 



After the above stated periods the insect breaks 

 through the upper end of the cocoon, by emitting a 

 liquid from its mouth, which moistens the gum with 

 which it h as lined the interior of its chamber. After 

 this operation it appears as the perfect insect, with 

 four wings of a grayish white colour,with two trans- 



verse undulated bands on the fore and hind wings. 

 The stationary and sluggish habits of these moths 

 are not entirely owing, as is generally supposed, to 

 the insect being confined within certain limits during 

 the period of several generations ; as these habits 

 are also common to others of the same family, 

 which are only found in certain local districts ; and 

 this proves that this valuable insect partakes of the 

 same mode of life in the domestic as in the wild or 

 natural state. Their life continues for the short 

 period of two or three days, in which time they are 

 wholly occupied in securing the continuance of 



