If in the month of March one passes through the fields, which are
beginning to get green, or through the woods, still deprived of their
leaves, there may be seen, hovering hither and thither, great hairy
insects, resembling gigantic bees. These are the females of a species
of bee, called by the French "bourdons," from the buzzing noise they
produce; and by us "humble bees," probably from their German name
"hummel," given for the same reason. These females have been awakened
by the spring sun. They examine the cavities of stones, the heaps of
moss, and the holes in banks, &c., seeking for a suitable spot to
construct a nest for their progeny.
The humble bees are of the same family as the bees, whom they resemble
in their organisation. Like them, they are divided into males,
females, and neuters, or workers. But their companies only last a
year. At the end of autumn the whole population has become extinct,
with the exception of the pregnant females, which pass the winter in a
state of torpor at the bottom of some hole, where they wait till the
spring to perpetuate their race. Their societies comprise generally
only a small number of individuals, from fifty to three hundred. They
are of peaceful habits, their ephemeral existence beginning and ending
with the flower season.
The humble bees are known by their great size, their short, robust
body, encircled by bands of very bright colours, and by the noise they
make in flying. Their hind legs are armed with two spurs. The females
and the workers have the same organisation for plundering flowers as
the bees have: they have similar trunks, and their legs are fitted
with brushes and baskets for gathering pollen. The males, like the
males of hive bees, have no sting. The greater number have their
dwelling-places underground; others make their nests on the surface of
the soil, in the cracks of walls, in heaps of stones, &c. The former
establish themselves in cavities situated as far as half a yard
underground, and approached by a long narrow gallery. It is almost
always a solitary female who has been the architect of the nest. She
cleans out the cavity she has chosen, makes it as smooth as possible,
and lines it with leaves and moss, to embellish the subterranean house
in which she is to pass nearly all her existence.
[Illustration: Fig. 333.--Male Humble Bee.]
The Moss Humble Bee (_Bombus muscorum_), called also the _Carding
Bee_, chooses an excavation of very little depth in which to make its
nest, or else itself undertakes the hollowing out of a hole in the
ground. It covers this with a dome of moss or dry herbs. But it does
not fly when transporting the moss, it drags it along the ground, with
its back turned towards the nest. Having seized a packet of the moss,
it sets to work to draw out the bits with its mandibles, and then
pushing them under its body, throws them in the direction of the nest
by a sort of kick from its hind legs. Sometimes, towards the end of
the season, many humble bees are to be seen working in line. The first
seizes the moss, and after having carded it, passes it under its body,
and throws it to the second, which throws it on to the third, and so
on, up to the nest. When the materials are ready, the insect makes use
of them to manufacture a sort of hemispherical lid, or covering,
resembling felt, which shuts the nest in, and is lined with wax. If
you lift up this covering, or small dome, which it is not dangerous to
do, for humble bees are not very aggressive, you find beneath it a
nest composed of a coarse comb.
The cells which compose the nest, and which are to receive the larvæ
of the insect, are of an oval shape, and of a pale yellow or even of a
blackish colour. Fig. 334 represents these cells. The wax of which
they are composed has none of the qualities of that of hive bees, but
is soft, sticky, and brownish.
[Illustration: Fig. 334.--Cells from a Humble Bee's nest.]
When the mother humble bee--which at first was alone and built her
house single-handed--has made a certain number of cells, she seeks for
honey and pollen, and prepares a paste, which she deposits in the
future cradles. She then lays six or seven eggs in each. The larvæ
which come from them live in common, at the same table, under the same
tent. The cell is at first only the size of a pea; it soon becomes too
narrow, splits and cracks, and requires to be enlarged and repaired
many times, a work of which our industrious insects acquit themselves
with a good deal of care and attention. Before passing into the pupa
state each larva spins for itself a shell or cocoon of very fine white
silk. It ceases to eat, remains at first rolled up, then expands
itself little by little, and changes its skin after three days. It
passes fifteen days in the pupa state in a quiescent condition. After
the normal time has elapsed for it to remain in its hiding-place, it
delivers itself from its mummy-like covering, with the help of the
mother or the workers. The humble bee then appears, robust, and its
body covered with a greyish down.
When the successive hatchings have furnished to the mother the
reinforcement she is waiting for, the workers she has raised occupy
themselves in building new cells, and in raising the wall of enclosure
which is to protect the nest. This wall, formed of wax, starts from
the base, and raises itself, like a vertical rampart, from every point
in the circumference. They then surmount this by the first roof, which
is flat, supported by some pillars, and in which they have left one or
two irregular openings. The whole is finally protected by a
hemispherical covering of moss, made into a sort of felt and lined
with wax. Fig. 335 represents, in its entirety, a nest of this humble
bee.
[Illustration: Fig. 335.--Nest of the Moss Humble Bee (_Bombus
muscorum_).]
The workers also take their part in rearing the eggs. They bring the
paste, which they slip into the cells to the larvæ by a small hole,
which is shut immediately afterwards. Later, they again give their
assistance in disengaging the pupæ from their envelopes. In short,
they make themselves generally useful; but they have one bad fault:
they are very fond of eating the eggs laid by the mother. They try to
seize them as she deposits them, or drag them from the cells, and suck
their contents. And so the mother is obliged to be incessantly
defending her eggs against the voracity of the workers, and to be
constantly on her guard, so as to be ready to drive away these
marauders from cells newly filled.
We owe to an English naturalist, Newport, the knowledge of another
curious fact relating to the laying of humble bees, which is the
expedient the females and the males have recourse to for hastening the
hatching of the eggs. They place themselves, like fowls sitting on
their eggs, over the cocoons containing the pupæ almost hatched. By
breathing quickly, these industrious insects raise the temperature of
their bodies, and consequently that of the air in the cells. Thanks to
this supplementary heat, the metamorphosis of the pupæ is much
hastened. Newport, by slipping miniature thermometers between the
cocoons of the nymphs and the sitting humble bees, ascertained that
the temperature of the latter was about 34° C., whilst the temperature
of the cocoons left to themselves was only 27° C.; that of the air in
the rest of the nest being only from 21° to 24° C. After many hours of
incubation, at the same time natural and artificial, in which Art and
Nature are so closely allied, after the sitting insects have many
times relieved one another, the young humble bees come out of their
cells. They are at first soft, greyish, moist, and very susceptible to
cold. But after a few hours they become stronger, and the yellow and
black bands with which their abdomens are surrounded begin to be
marked out. The spring laying produces exclusively workers. The
greatest abundance of eggs are laid in August and September. The
laying of the female eggs begins in July; that of the males follows
soon after.
Until autumn the humble bees are incessantly enlarging their nests,
and multiplying their little pots of honey. Without accumulating a
great stock of provisions, for which they have no occasion, they
always keep in reserve a quantity of pollen and honey for their daily
wants. The cells in which the honey is stored differ very much in
shape. Some species of humble bees give them long and narrow necks;
others, less _recherché_ in their style of construction, simply make
cylindrical vases. There are among the humble bees races of artists
and races of simple builders; the one construct with taste, the other
only seek the useful.
During the day the humble bees cull honey from the flowers. At night
they enter their home; but a certain number take the liberty of
sleeping out. Surprised by the arrival of night in the bottom of the
calyx of a sweetly-scented flower, they philosophically determine to
sleep in the open air, lying on this perfumed bed, with the heaven as
their canopy.
The coupling of the humble bees takes place towards the end of
September. It costs the males their life, as it does with the hive
bees. The impregnated females do not lay till the following spring; it
is they who, after the winter is passed, will become the mothers of
new generations. They will take the reins of the family when the
mother who founded the colony, the males, as also the workers, shall,
according to the laws of Nature, have passed away. There are often, on
the other hand, some workers which, born in the spring, become
fruitful, and lay the same year, but only the eggs of males. These
become a butt for the jealousy of the reigning mother, who pursues
them with fury, and devours their eggs. These, however, have
themselves cruel hearts. Animated by a profound jealousy, they dispute
the occupancy of the cells savagely, so as to be able to lay a few
eggs in them, which are no sooner laid than they are destroyed by
their savage sisters. However, they never make use of their stings in
any of these attacks. The humble bee population is peaceful, even in
its combats. After the first cold weather in autumn, all these
insects, as we have said, perish, except the pregnant females. These
privileged depositaries of the race, _spes altera domûs_, look for a
place of retreat, and there sleep till the following spring. Then they
wake up and found new colonies, which continue the race.
For a long while were confounded with the humble bees certain insects
which have the same appearance, that is to say, a hairy body, with
bands of various colours, but whose hind legs are adapted neither for
gathering honey nor for building. These are the genus _Psithyrus_: it
was Lepelletier de Saint-Fargeau who discovered their true position.
These are parasites, and only consist of males and fertile females,
without workers. They lay their eggs in the nest of the humble bee.
They are, indeed, so like their hosts, that they can introduce
themselves into their dwellings without raising any suspicion. The
humble bees admit them freely, and receive them as if they belonged to
the family; so much so, indeed, that the poor humble bees themselves
bring up the larvæ of these impudent guests. In the Order Hymenoptera
one meets with many examples of these sorts of parasites, which instal
their progeny in the nest of another insect, as the cuckoo does in the
nests of other birds.