THE BROWN-TAILED MOTH. 55 
white, and very tough, clinging to the scissors so that a 
straight cut is almost impossible. Delicate walls divide 
the interior into several compartments, in all of which are 
evidences that the caterpillars must have resided for some 
time. The reason why the creatures make this nest is, 
that they are hatched towards the end of summer, and in 
consequence are forced to pass the winter in the larval con- 
dition, 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 enclose 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. 
There is an allied insect, popularly called the BRown- 
TAILED Motu, 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 sur- 
rounding 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. 
These nests are very firmly constructed, and the walls 
are solid, as is needful for insects which are obliged to pass 
the winter within them. There are, however, many cater- 
pillars which live socially, and which spin a common 
habitation, but which leave it before the cold weather comes 
on, and, in consequence, do not need such thick walls. Any 
hedgerows where nettles are found will supply numerous 
examples of such nests, made by the curious caterpillars 
which afterwards assume the lovely and familiar forms 
