The Mason-Bees | Page 9

she comes out and once
more goes in head first. It is a question of stirring the materials, with
her mandibles for a spoon, and making the whole into a homogeneous
mixture. This mixing-operation is not repeated after every journey: it
takes place only at long intervals, when a considerable quantity of
material has been accumulated.
The victualling is complete when the cell is half full. An egg must now
be laid on the top of the paste and the house must be closed. All this is
done without delay. The cover consists of a lid of pure mortar, which
the Bee builds by degrees, working from the circumference to the
centre. Two days at most appeared to me to be enough for everything,
provided that no bad weather--rain or merely clouds--came to interrupt
the labour. Then a second cell is built, backing on the first and
provisioned in the same manner. A third, a fourth, and so on follow,
each supplied with honey and an egg and closed before the foundations
of the next are laid. Each task begun is continued until it is quite
finished; the Bee never commences a new cell until the four processes
needed for the construction of its predecessor are completed: the
building, the victualling, the laying of the egg and the closing of the
cell.
As the Mason-bee of the Walls always works by herself on the pebble
which she has chosen and even shows herself very jealous of her site
when her neighbours alight upon it, the number of cells set back to
back upon one pebble is not large, usually varying between six and ten.
Do some eight grubs represent the Bee's whole family? Or does she
afterwards go and establish a more numerous progeny on other
boulders? The surface of the same stone is spacious enough to provide
a support for further cells if the number of eggs called for them; the
Bee could build there very comfortably, without hunting for another
site, without leaving the pebble to which she is attached by habit and
long acquaintance. It seems to me therefore, exceedingly probable that
the family is a small one and that it is all installed on the one stone, at
any rate when the Mason-bee is building a new home.
The six to ten cells composing the cluster are certainly a solid dwelling,
with their rustic gravel covering; but the thickness of their walls and
lids, two millimetres (.078 inch--Translator's Note.) at most, seems

hardly sufficient to protect the grubs against the inclemencies of the
weather. Set on its pebble in the open air, without any sort of shelter,
the nest will have to undergo the heat of summer, which will turn each
cell into a stifling furnace, followed by the autumn rains, which will
slowly wear away the stonework, and by the winter frosts, which will
crumble what the rains have respected. However hard the cement may
be, can it possibly resist all these agents of destruction? And, even if it
does resist, will not the grubs, sheltered by too thin a wall, have to
suffer from excess of heat in summer and of cold in winter?
Without arguing all this out, the Bee nevertheless acts wisely. When all
the cells are finished, she builds a thick cover over the group, formed of
a material, impermeable to water and a bad conductor of heat, which
acts as a protection at the same time against damp, heat and cold. This
material is the usual mortar, made of earth mixed with saliva, but on
this occasion with no small stones in it. The Bee applies it pellet by
pellet, trowelful by trowelful, to the depth of a centimetre (.39
inch--Translator's Note.) over the cluster of cells, which disappear
entirely under the clay covering. When this is done, the nest has the
shape of a rough dome, equal in size to half an orange. One would take
it for a round lump of mud which had been thrown and half crushed
against a stone and had then dried where it was. Nothing outside
betrays the contents, no semblance of cells, no semblance of work. To
the inexperienced eye, it is a chance splash of mud and nothing more.
This outer covering dries as quickly as do our hydraulic cements; and
the nest is now almost as hard as a stone. It takes a knife with a strong
blade to break open the edifice. And I would add, in conclusion, that,
under its final form, the nest in no way recalls the original work, so
much so that one would imagine the cells of the start, those elegant
turrets covered with stucco-work, and the dome of the finish, looking
like a mere lump of mud, to be the product of two different