from the floor above. She cuts a fairly clean hole in it, shaped like
a truncate cone, having its larger base on the side where the Bee is
and its smaller base opposite. This conformation of the exit-door is
a characteristic of the work. When the insect tries to attack the
diaphragm, it first digs more or less at random; then, as the boring
progresses, the action is concentrated upon an area which narrows
until it presents no more than just the necessary passage. Nor is the
cone-shaped aperture special to the Osmia: I have seen it made by the
other bramble-dwellers through my thick disks of sorghum-pith. Under
natural conditions, the partitions, which, for that matter, are very
thin, are destroyed absolutely, for the contraction of the cell at
the top leaves barely the width which the insect needs. The truncate,
cone-shaped breach has often been of great use to me. Its wide base
made it possible for me, without being present at the work, to judge
which of the two neighbouring Osmiae had pierced the partition; it
told me the direction of a nocturnal migration which I had been
unable to witness.

The first-hatched Osmia, wherever she may be, has made a hole in her
ceiling. She is now in the presence of the next cocoon, with her head
at the opening of the hole. In front of her sister's cradle, she
usually stops, consumed with shyness; she draws back into her cell,
flounders among the shreds of the cocoon and the wreckage of the
ruined ceiling; she waits a day, two days, three days, more if
necessary. Should impatience gain the upper hand, she tries to slip
between the wall of the tunnel and the cocoon that blocks the way.
She even undertakes the laborious work of gnawing at the wall, so as
to widen the interval, if possible. We find these attempts, in the
shaft of a bramble, at places where the pith is removed down to the
very wood, where the wood itself is gnawed to some depth. I need