new cell,
to cleaning out the dirt and rubbish of the other species. I frequently
find these bees remaining for a long time on the wing close to the
opening, and bobbing their heads against the side, as if fanning air
into the opening. I have seen them thus employed for twenty minutes.
Whether one bee or more makes the tunnel, that is, whether they take
turns in boring, I cannot at present say. In opening the cells (Fig.
21), more than one are generally found, even at this season. About two
weeks ago; I found as many as seven, I think, in one."[3]

The hole is divided by partitions into cells about seven-tenths of an
inch long. These partitions are constructed of the coarse dust or
chippings made by the bee in eating out her cells, for our active little
carpenter is provided with strong cutting jaws, moved by powerful
muscles, and on her legs are stiff brushes of hair for cleaning out the
tunnel as she descends into the heart of the solid wood. She must throw
out the chips she bites off with her powerful mandibles from the sides
of the burrow, by means of her hind legs, passing the load of chips
backwards out of the cell with her fore limbs, which she uses as hands.

[Illustration: 20. Larva and Pupa of Anthrax.]

The partitions are built most elaborately of a single flattened band of
chips, which is rolled up into a coil four layers deep. One side,
forming the bottom of the cell, is concave, being beaten down and
smoothed off by the bee. The other side of the partition, forming the
top of the cell, is flat and rough.

[Illustration: 21. Nest of Carpenter Bee.]

At the time of opening the burrow, July 8th, the cells contained nearly
full-grown larvae, with some half developed. They were feeding on the
masses of pollen, which were as large as a thick kidney bean, and
occupied nearly half the cell. The larvae (Fig. 21) resemble those of the
Humble bee, but are slenderer, tapering more rapidly towards each end of
the body.

The habits and structure of the little green Ceratina ally it closely
with Xylocopa. This pretty bee, named Ceratina dupla by Mr. Say, tunnels
out the stems of the elder or blackberry, syringa, or any pithy shrub,
excavating them often to a depth of six or seven inches. She makes the
walls just wide enough to admit her body, and of a depth capable of
holding three or four, often five or six cells (Fig. 22). The finely
built cells, with their delicate silken walls, are cylindrical and
nearly squar