198 THE LIFE OF AN INSECT. 



which are called cocoons, in which they wrap 

 themselves up close during the period to be de- 

 voted to the pupa state. Let us speak of these 

 each separately ; and, first, of the case, or cocoon, 

 as a place of concealment for the larva. It is 

 right, however, to premise, that, while the greater 

 number of insects are in a torpid or half-torpid 

 state while in the pupa form, all are not so, as 

 will be noticed in the next chapter; and those 

 which are not do not of course require the pro- 

 tection of a cocoon, or the contrivance of a silken 

 hammock. 



The material of which the case or cocoon is 

 composed is a beautiful silken fibre, which is fur- 

 nished by a spinning apparatus placed either at 

 the extremity of the body, or more frequently at 

 the mouth of the insect, whence it proceeds in a 

 filament of the utmost delicacy and transparency, 

 but at the same time of considerable tenacity. 

 By its means alone cocoons, of a number of 

 different kinds, some of extraordinary beauty and 

 ingenuity, are constructed ; but in other cases 

 the insect has recourse to various materials to 

 assist in giving strength to the walls of its cell. 



The best example, and the most familiar one we 



