roughly. Less skilful
than the others, it does not amass at once all the provisions which
its larvae will need during the period of evolution. When the offspring
has absorbed the last prey brought, it is necessary to bring a new
victim. This insect is scarcely more advanced than birds, who feed
their young from day to day. And it is a great labour to re-open every
time the gallery which leads to the nursery; on all these visits, in
fact, the _Bembex_ fills it up on leaving, and causes the
disappearance of all revealing traces. It is obliged to take so much
trouble, because it has not inherited from its ancestors the receipt
for the paralysing sting; it throws itself without care on its victim,
delivers a few chance blows, and kills it. Necessarily it cannot,
under these conditions, lay up provisions for the future; they would
corrupt, and the larvae would not be benefited; hence the obligation of
frequently returning to the nest, and of a perpetual hunt to feed
descendants whom nature has gifted with an excellent appetite.
According to the age of the offspring, the mother chooses prey of
different sizes; at first she brings small Diptera; then, when it has
grown, she captures for it large blow-flies, and lastly gadflies.[79]
It will be seen, then, that if we suppose the instinct of the _Sphex_
to be slowly developed by being derived from a sting given at random,
we make a supposition which is quite admissible and rests on
ascertained facts. However this may be, the _Bembex_, returning to its
burrow, is able to find it again with marvellous certainty, in spite
of the care taken to hide it by removing every trace that might reveal
its existence. It is guided by an extraordinary topographic instinct,
which men not only do not possess, but cannot even understand the
nature of.

[78] _Souvenirs entomologiques_, 1879, pp. 225 _et seq._

[79] A Wasp found in La Plata, the _Monedula punctata_, as
described by Hudson (_Naturalist in La Plata_, pp. 162-164),
is an adroit fly-catcher, and thus supplies her grub with
fresh food, carefully covering the mouth of the hole with
loose earth after each visit; as many as six or seven
freshly-killed insects may be found for the use of one grub.

It would appear that certain Hymenoptera, fearing to kill their victim
with the sting, and not knowing the art of skilful lesions, attempt to
immobilise them by wounds of another sort. This is the c