0 ?O 
THE STUDY OF INSECTS. 
sons, have gained an idea of what goes on in a single nest. 
There are two broods each year. The mature bees of the 
fall brood winter in the nests. 
The Large Carpenter-bee, Xylocopa virginica (Xy-loc'o-pa 
vir-gin'i-ca).—This is a large insect, resembling a bumblebee 
in size, and somewhat in appearance. But it can be easily 
distinguished from a bumblebee, as the female has a dense 
brush of hairs on the hind leg, instead of a basket for carry¬ 
ing pollen. This bee builds its nest in solid wood, and some¬ 
times excavates a tunnel a foot in length. These tunnels 
are similar to those of the carpenter-wasp, Monobia quadri- 
dens (Fig. 788); but differ in being provisioned with a paste 
of pollen and nectar, and in the structure of the partitions. 
These are made of chips of wood, securely cemented to¬ 
gether, and arranged in a closely-wound spiral. This 
arrangement of the chips is easily seen when the lower side 
of a partition is examined ; but the upper side of a partition, 
which forms the floor of the cell above it, is made concave 
and very smooth, so that the arrangement of the chips is 
not visible. 
II. THE GUEST-BEES OR INQUILINES. 
Although bees are proverbially industrious, we find 
many loafers in the family. We do not refer to the lazy 
males of those species in which the females are hard workers, 
but to certain species in which both sexes are alike idle, 
and dependent upon the exertions of other species of bees. 
These idle species are called guest-bees, or inquilines, be¬ 
cause they are reared in the nests of other bees, who act, 
willingly or unwillingly, as hosts. 
The guest-bees are entertained both by solitary bees and 
by social bees; but each species of guest-bee inhabits the 
nests of a particular kind of working bee. Thus the nests 
of certain bees are visited by certain guest-bees, while those 
of other species are infested by different guests. This habit 
of sponging their living has had a degrading effect on the 
guest-bees; for we find that they are not merely idle, but 
