330 INSECT AUCHITECTURE. 



J)y the colonists; but from minute observation of 

 at least twenty of these nests in the winter of 

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

 an accidental, and not a necessary part of the struc- 

 ture. When a leaf happens to be in the line of the 

 walls of the nest, it is included; but there is no appa- 

 rent design in pressing it into the service, nor is a 

 branch selected because it is leafy. On the con- 

 trary, 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 somewhat egg-shaped; but when there arc 

 several twigs, it commonly joins each, assuming an 

 angular shape, as may be seen in the figure. 



WinttT nest of the Social Catcrjnllars of the Brcivr. tail Moth 

 (Poithesia awviQw^), fig^nrcd f om specimen. 



