OBSERVATIONS ON THE LEAF-CUTTING BEE. 29
pieces of leaf are brought and placed in position, if too large
portions are cut off and masticated and then used to stop any
crevices. The number used varies from about twelve to four-
teen. On one occasion, however, I counted thirty-eight. As the
work is nearing completion the whole surface is composed of
leaf mortar made by masticating the leaves ; to this are added
small fragments of wood, the whole forming a kind of reinforced
concrete. I think the great care taken was to ensure that no-
leakage of food should take place into the lower cells. As the
tubes were made from sound timber, with the walls quite smooth,
the bees experienced considerable difficulty in detaching splinters
from the sides, and frequent visits were paid to neighbouring
tubes, where the entrance holes offered a better chance of obtain-
ing the desired material, they being cut across the grain of the
wood.
I had observed that during the work of sealing the cells, the
bee would occasionally leave the nest, apparently to get a fresh
piece of leaf, but, returning in a few seconds, would do a little
touching up, as if not quite satisfied with the work. A few days
later an incident occurred that seemed to throw light on this
peculiar behaviour.
I had observed a strange bee about for several days, and.
had noticed it entering several of the tubes, both empty ones,
and those in which cell making was in progress ; its entrance
and exit were so rapid that I had no chance to examine it. As
it was a comparatively small bee I thought it might not approve
of the larger tube, and so decided to tempt it with a smaller
one, but as I had at the time three leaf-cutters under observation
I let the matter slide. The following day a fresh tube was
occupied, again by a leaf-cutter. In the course of the clay this
bee completed one cell ; I watched it lay its egg. After doing
this it spent some time working at the upper portion of the cell,
at the point where the dividing wall between the first and second
cells would be formed. Owing to the leafy side walls being high.
I could not see what took place, but imagine some kind of
stop was made to receive the first section of leaf ; this was
soon brought ; on being pressed down it stayed exactly where
the work, whatever it was, had been done.
At this time I noticed that the strange bee, seen on previous
days, had settled on the side of the nesting box in such a position.