the creature's continual comings and
goings would result in a landslip.

A matter less easy of explanation is the complete disappearance of the
material which originally filled the excavated space. Where are the
twelve cubic inches of earth that represent the average volume of the
original contents of the shaft? There is not a trace of this material
outside, nor inside either. And how, in a soil as dry as a cinder, is
the plaster made with which the walls are covered?

Larvae which burrow in wood, such as those of Capricornis and Buprestes,
will apparently answer our first question. They make their way through
the substance of a tree-trunk, boring their galleries by the simple
method of eating the material in front of them. Detached by their
mandibles, fragment by fragment, the material is digested. It passes
from end to end through the body of the pioneer, yields during its
passage its meagre nutritive principles, and accumulates behind it,
obstructing the passage, by which the larva will never return. The work
of extreme division, effected partly by the mandibles and partly by the
stomach, makes the digested material more compact than the intact wood,
from which it follows that there is always a little free space at the
head of the gallery, in which the caterpillar works and lives; it is not
of any great length, but just suffices for the movements of the
prisoner.

Must not the larva of the Cigale bore its passage in some such fashion?
I do not mean that the results of excavation pass through its body--for
earth, even the softest mould, could form no possible part of its diet.
But is not the material detached simply thrust back behind the excavator
as the work progresses?

The Cigale passes four years under ground. This long life is not spent,
of course, at the bottom of the well I have just described; that is
merely a resting-place preparatory to its appearance on the face of the
earth. The larva comes from elsewhere; doubtless from a considerable
distance. It is a vagabond, roaming from one root to another and
implanting its rostrum. When it moves, either to flee from the upper
layers of the soil, which in winter become too cold, or to install
itself upon a more juicy root, it makes a road by rejecting behind it
the material broken up by the teeth of its picks. That this is its
method is incontestable.

As with the larvae of Capricornis and Buprestes, it is enough for the
traveller to have around it the small