170 
STRANGE DWELLINGS. 
The handsome Oak Egger Moth ( Gasiropacha quercus ) 
affords another example of the pensile cocoon. Of these insects 
also I have had great numbers ; and some specimens of the 
moth, chrysalis, and cocoon are now before me, the cocoon un- 
changed by the eighteen years which have elapsed since it was 
made, but the moth sadly faded, after the manner of its kind 
when exposed to the action of light. 
Large as is the caterpillar of the Oak Egger moth, it is con- 
tracted into a comparadvely small chrysalis when it assumes 
the pupal state, and makes a cocoon which only allows enough 
space for the pupa and the cast larval skin. The form of the 
cocoon is egg-shaped, whence the name of Oak Egger, and its 
substance is rather peculiar, being thin, hard, and rather brittle ji 
when quite dry. Externally it is surrounded by a loose layer 
of silken threads, by means of which it is attached to the plant 
on which it hangs ; but the cocoon itself is smooth, very much 
the colour of half-charred paper, and in spite of its brittleness is 
possessed of some elasticity. 
There is a smaller insect, popularly called the Little Egger 
Moth [Er togas ter lanestris ), which spins a cocoon of a similar 
structure, except that the walls are of even harder and more 
uniform texture, scarcely larger than a wren’s egg, and of a | 
substance which looks almost as if it were made of the same 
material as the egg. When broken, it is found to be even more 
brittle than that of the larger insect. Owing, in all probability, 
to the exceeding closeness of the structure, which would exclude 
air from the inhabitant, it is perforated with one or two very 
tiny and very circular holes, which look just as if some one had 
been trying to kill the insect by piercing the cocoon with a fine 
needle or pin. 
Even from the outside these perforations are visible, but they 
are much more evident when the cocoon is opened. The ob- 
ject of these holes is, however, conjectural, and it would be a 
useful experiment to>stop them with wax, in order to see whether 
the inclosed insect could be developed when the air was thus 
excluded. I believe that there are none of these holes in the 
