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 larvæ of Capricornis and Buprestes, it is enough for the
traveller to have around it the small amount of free space necessitated
by its movements. Moist, soft, and easily compressible soil is to the
larva of the Cigale what digested wood-pulp is to the others. It is
compressed without difficulty, and so leaves a vacant space.

The difficulty is that sometimes the burrow of exit from the