228 STATES OF INSECTS. (Larva.) 
they fasten together with a glutinous secretion. The 
same material is employed by others in forming a co- 
coon wholly of earth; which is sometimes, as that of 
the stag-beetle, Lucanus Cervus, exceedingly hard; at 
others, as that of some moths, Noctua ambigua, &c. 
so slight as to fall to pieces as soon as touched *. Other 
cocoons are formed of grains of earth. Reaumur has 
given a very interesting account of the procedures of a 
larva in repairing one of these cocoons, from which he 
had broken off the top when just completed. Without 
quitting the interior of the walls that remained, it put 
out its head from the breach, and for more than an hour 
employed itself in selecting one by one grains of earth, 
which it conveyed with its mandibles and deposited with- 
in its case: it next spun all round the opening, threads 
of silk, to which it attached grains of earth taken from 
the previously-stored heap, uniting them compactly by 
means of other silken threads. After employing three 
hours in this laborious process, the industrious little 
mason had reduced the diameter of the breach to a few 
lines. Reaumur was very curious to know how it would 
fill up this orifice, which would no longer admit the 
protrusion of its head outside the walls, as in its previous 
operations. He concluded, that while the rest of the 
cocoon was exteriorly formed of earth, this opening 
would be merely closed with silk. He was mistaken, 
however: the artist knew how to vary its manoeuvres, 
and make its vault of one uniform texture. It spun 
across the opening a little net of silk, between the meshes 
a Wien. Verz. I possess a cocoon of this kind from New Hol- 
land, even now quite solid, and retaining its form. No silk appears 
to have been used in its composition. 
