paralysis at first affects only the legs
whose ganglion is attacked; next, it spreads slowly to the second
pair; lastly, it reaches the third. The local effect is diffused. This
diffusion, which might well take place in the victims of the predatory
insects, plays no part in the latters' method of operation. The egg,
which will be laid immediately afterwards, demands the complete inertia
of the prey from the outset. Hence all the nerve-centres that govern
locomotion must be numbed instantaneously by the virus.

I can now understand why the poison of the predatory Wasps is
comparatively painless in its effects. If it possessed the strength of
that of the Bee, a single stab would impair the vitality of the prey,
while leaving it for some days capable of violent movements that would
be very dangerous to the huntress and especially to the egg. More
moderate in its action, it is instilled at the different nervous
centres, as is the case more particularly with the caterpillars.
(Caterpillars are the prey of the Ammophila, which administers a
separate stab to each of the several ganglia.--Translator's Note.)
In this way, the requisite immobility is obtained at once; and,
notwithstanding the number of wounds, the victim is not a speedy corpse.
To the marvels of the paralysers' talent we must add one more: their
wonderful poison, the strength of which is regulated by delicate doses.
The Bee revenging herself intensifies the virulence of her poison; the
Sphex putting her grubs' provender to sleep weakens it, reduces it to
what is strictly necessary.

One more instance of nearly the same kind. I prefer to take my subjects
from among the Orthoptera, which, owing to their imposing size and the
thinness of their skin at the points to be attacked, lend themselves
better than other insects to my delicate manipulations. The armour of
a Buprestis, the fat blubber of a Rosechafer-grub, the contortions of
a caterpillar present almost insuperable obstacles to the success of
a sting which it is not in my power to direct. The insect which I
now offer to the Bee's lancet is the Great Green Grasshopper (Locusta
viridissima), the adult female. The prick is given in the median line of
the fore-legs.

The effect is overwhelming. For two or three seconds the insect writhes
in convulsions and then falls on its side, motionless throughout,
save in the ovipositor and the antennae. Nothing stirs so long as the
creature is left alone; but, if I tickl