272 
STRANGE D WE LUNGS. 
me. It was found in a hedge, about two feet from the 
ground, and is rather a complicated structure. The scaffolding, 
so to speak, of the nest is formed by a horizontal spray of 
three small twigs, and it is strengthened by the long hedge- 
grass which crossed the spray. Seeds of different kinds are 
woven into the walls, so that a comparatively small portion of ; 
the silk is exposed to view. 
When cut open, it shows a singularly beautiful structure 
within. There are several sheets of silken tissue, each be- 
coming more delicate, and the innermost being white, shining 
like satin ; whereas the outer covering is dull- white, and very ! 
tough, clinging to the scissors so that a straight cut is almost | 
impossible. Delicate walls divide the interior into several i 
compartments, in all of which are evidences that the caterpillars 
must have resided for some time. The reason why the crea- I 
tures make this nest is, that they are hatched towards the end j 
of summer, and in consequence are forced to pass the winter in 
the larval condition, so that some warm residence is needful ! 
for them. It is well known that air is a very bad conductor of 
heat, and, in consequence, the successive sheets of silk which ! 
cover the nest, and which inclose layers of air between them, 
form a protection which is far warmer than would be obtained 
by a solid mass of silk measuring twice the thickness of the 
three walls, together with their intervening spaces. 
i 
There is an allied insect, popularly called the Brown-tailed 
Moth ( Porthesia auriflud), which spins a social nest that in 
many respects resembles that of the Gold-tailed Moth. The 
nest, however, is scarcely so elegant, nor is the silken web so 
beautifully delicate. Much, however, depends upon surrounding 
conditions, such as the disposition of the twig on which the nest 
is placed, and the presence or absence of leaves, whether those 
of the tree or of other plants that happen to grow in close 
proximity. 
