done she bores a second passage, provisions it, and lays another egg,
closes up the orifice, and proceeds to prepare the third. This work is
pushed on with great activity, and when completed the _Sphex_ entirely
fills up the subterranean passage, and completely isolates the hope of
the race at a depth sufficient to shelter it well. A last precaution
is taken: before leaving, the rubbish in front of the obstructed
opening is cleared away, and every trace of the operation disappears.
The nest is then definitely abandoned, and another one prepared.

[72] "Etude sur l'instinct et les metamorphoses des
Sphegiens," _Ann. Sci. Nat._, 1856.

The chambers in which the larvae are enclosed--hastily made with little
care, and with rough unsmoothed walls--are not very solid, and could
not last long without slipping; but as they only have to last for a
single season they possess sufficient resistance for the insect's
purpose. The larva also knows very well how to protect itself against
the roughness of the walls, and overlays them with a silky secretion
produced by its glands.

We have now to consider the nature of the provisions placed by the
_Sphex_ near the egg. Each cell must contain four crickets. That is
the amount of food necessary for a larva during its evolution, and
these insects are in fact large enough to supply a considerable amount
of nourishment. When the _Sphex_ interrupts digging operations it is
to fly on a hunting expedition. It soon returns with a cricket it has
seized, holding it by one antenna which it turns round in its jaws. It
is a heavy burden for the slender _Sphex_ to bear. Sometimes on foot,
dragging its burden after it, sometimes flying, and carrying the
suspended cricket always in a passive condition, the burrow is
gradually reached, not without difficulty. In spite of appearances,
the cricket is not dead; it cannot move, but if kept for several days
it will not putrefy, and its joints remain supple. It is simply the
victim of a general paralysis.

_The cause of the paralysis._--It was evidently of the greatest
interest to know how the _Sphex_ contrived this capture, and what
method it used to suppress the movements of the prey. In order to
obtain the solution of this problem, Fabre during a long period
accumulated experiments and observations, and at last discovered in
every detail how the thing was done. In order to compel the _Sphex_ to
act in his presence, he placed himself in front