330 INSECT ARCHITECTURE. 



by 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 ap- 

 parent 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 are several 

 twigs, it commonly joins each, assuming an angular 

 shape, as may be seen in the figure. 



/Pinter nestofthe Social Caterpillars of the Brown-tail Moth 

 (Port)iL'sia auriftun), figured from specimen. 



