ater. We
have only to keep a Wasp grub in a little glass tube to recognize these
occasional discharges. Well, I see nothing else to explain the action of
the Volucella's grubs when they dip into the cells without wounding the
larvae. They are looking for this liquid, they provoke its emission.
It represents to them a dainty which they enjoy over and above the more
substantial fare provided by the corpses.

The bumblebee fly, that sanitary inspector of the Vespine city, fulfils
a double office: she wipes the wasp's children and she rids the nest of
its dead. For this reason, she is peacefully received, as an auxiliary,
when she enters the burrow to lay her eggs; for this reason, her grub is
tolerated, nay more, respected, in the very heart of the dwelling, where
none might stray with impunity. I remember the brutal reception given
to the Saperda and Hylotoma grubs when I place them on a comb. Forthwith
grabbed, bruised and riddled with stings, the poor wretches perish. It
is quite a different matter with the offspring of the Volucella.
They come and go as they please, poke about in the cells, elbow the
inhabitants and remain unmolested. Let us give some instances of this
clemency, which is very strange in the irascible Wasp.

For a couple of hours, I fix my attention on a Volucella grub
established in a cell, side by side with the Wasp grub, the mistress
of the house. The hind quarters emerge, displaying their papillae.
Sometimes also the fore part, the head, shows, bending from side to side
with sudden, snake-like motions. The wasps have just filled their crops
at the honey pot; they are dispensing the rations, are very busily at
work; and things are taking place in broad daylight, on the table by the
window.

As they pass from cell to cell, the nurses repeatedly brush against and
stride across the Volucella grub. There is no doubt that they see
it. The intruder does not budge, or, if trodden on, curls up, only to
reappear the next moment. Some of the wasps stop, bend their heads
over the opening, seem to be making inquiries and then go off, without
troubling further about the state of things. One of them does something
even more remarkable: she tries to give a mouthful to the lawful
occupant of the cell; but the larva, which is being squeezed by its
visitor, has no appetite and refuses. Without the least sign of anxiety
on behalf of the nursling which she sees in awkward company, the wasp
retires and goes to distrib