l pieces supply the floor and sides; the smaller, round
pieces are reserved for the lid. A row of these thimbles, placed one on
top of the other, up to a dozen or more, though often there are less:
that is, roughly, the structure of the Leaf-cutter's nest.

When taken out of the recess in which the mother has manufactured it,
the cylinder of cells seems to be an indivisible whole, a sort of tunnel
obtained by lining with leaves some gallery dug underground. The real
thing does not correspond with its appearance: under the least pressure
of the fingers, the cylinder breaks up into equal sections, which are so
many compartments independent of their neighbours as regards both floor
and lid. This spontaneous break up shows us how the work is done. The
method agrees with those adopted by the other Bees. Instead of a
general scabbard of leaves, afterwards subdivided into compartments by
transverse partitions, the Megachile constructs a string of separate
wallets, each of which is finished before the next is begun.

A structure of this sort needs a sheath to keep the pieces in place
while giving them the proper shape. The bag of leaves, in fact, as
turned out by the worker, lacks stability; its numerous pieces, not
glued together, but simply placed one after the other, come apart and
give way as soon as they lose the support of the tunnel that keeps them
united. Later, when it spins its cocoon, the larva infuses a little
of its fluid silk into the gaps and solders the pieces to one another,
especially the inner ones, so much so that the insecure bag in due
course becomes a solid casket whose component parts it is no longer
possible to separate entirely.

The protective sheath, which is also a framework, is not the work of
the mother. Like the great majority of the Osmiae, the Megachiles do not
understand the art of making themselves a home straight away: they
want a borrowed lodging, which may vary considerably in character.
The deserted galleries of the Anthophorae, the burrows of the fat
Earth-worms, the tunnels bored in the trunks of trees by the larva of
the Cerambyx-beetle (The Capricorn, the essay on which has not yet been
published in English.--Translator's Note.), the ruined dwellings of
the Mason-bee of the Pebbles, the Snail-shell nests of the Three-horned
Osmia, reed-stumps, when these are handy, and crevices in the walls
are all so many homes for the Leaf-cutters, who choose this or that
establishment according t