212 Insect Architecture. 



two, or more together on the upper surface of a leaf. In 

 the course of six or eight weeks (during which time it 

 casts its skin thrice) it arrives at its full growth, when it 



Eggs of the Puss-Moth. 



is about as thick, and nearly as long, as a man's thumb, 

 and begins to prepare a structure in which the pupa may 

 sleep securely during the winter. As " we have, oftener than 

 once, seen this little architect at work, from the foundation 

 till the completion of its edifice, we are thereby enabled to 

 give the details of the process. 



The puss, it may be remarked, does not depend for pro- 

 tection on the hole of a tree, or the shelter of an overhang- 

 ing branch, but upon the solidity and strength of the fabric 

 which it rears. The material it commonly uses is the bark 

 of the tree upon which the cell is constructed ; but when 

 this cannot be procured, it is contented to employ whatever 

 analogous materials may be within reach. One which we 

 had shut up in a box substituted the marble paper it was 

 lined with for bark, which it could not procure.* With 



* It is justly remarked by Reaumur, that when caterpillars are left at 

 liberty among their native plants, it is only by lucky chance they can be ob- 

 served building their cocoons, because the greater number abandon the plants 

 upon which they have been feeding, to spin up in places at some distance. In 

 order to see their operations, they must be kept in confinement, particularly in 

 boxes with glazed doors, where they may be always under the eye of the natu- 

 ralist. In such circumstances, however, we may be ignorant what building 

 materials we ought to provide them with for their structures. A red cater- 

 pillar, with a few tufts of hair, which Reaumur found in July feeding upon 

 the flower bunches of the nettle, and refusing to touch the leaves, began in a 

 few days to prepare its cocoon, by gnawing the paper lid of the box in which 

 it was placed. This, of course, was a material which it could not have procured 

 in the fields, but it was the nearest in properties that it could procure ; for, 

 though it had the leaves and stems of nettles, it never used a single fragment 

 of either. When Reaumur found that it was likely to gnaw through the paper 



