352 



Insect Architecture. 



winter of 1828-9, we are quite satisfied that leaves are only 

 an accidental, and not a necessary, part of the structure. 

 When a leaf happens to be in the line of the walls of the 

 nest, it is included ; but there is no apparent design in 

 pressing it into the service, nor is a branch selected because 

 it is leafy. On the contrary, by far the greater number of 

 these nests do not contain a single leaf, but are composed 

 entirely of grey silk. In external form, no two of these 

 nests are alike ; as it depends entirely upon the form of the 

 branch. When, therefore, there is only one twig, it is some- 

 what egg-shaped; Jaut when there are several twigs, it 

 commonly joins each, assuming an angular shape, as may bo 

 seen in the left-hand figure. 



Winter nests of Pnrthesia clirysorrlirra, one being cut op?n to show the chambers. 

 The dots repre&ent the ogebtu of the caterpillars. 



This irregularity arises from the circumstance of each 

 individual acting on its own account, without the direction 

 or superintendence of the others. The interior of the 

 structure is, for the same reason, more regular, being divided 

 into compartments, each of which forms a chamber for one 

 or more individuals. Previous to the cold weather, these 



