Welcome to the online training for the Wisconsin Bumble Bee Brigade, a statewide
citizen-based monitoring project. This training is divided into multiple parts,
all of which are available through this YouTube playlist.  This video provides an
introduction to bumble bee biology.
Wisconsin has 400-500 species of native bees. Of those, most-
about 85% are solitary. That means they do not live communally in colonies.
The rest are social or semi social meaning they live together in colonies.
This includes our 20 species of native
bumblebees.We also have one species of
non-native social bee in Wisconsin. That's
the European honeybee. Honeybees are not
native to the US. They are an agricultural species classified as
livestock by the state.
As stated
bumblebees are social; they live together
in colonies with a queen, workers which
are also female, and males. They have
annual colonies meaning they last for
only one year. Bumble bees are found in
many habitats,  usually where a continuous
supply of pollen and nectar, which is
what they eat, is available throughout
the growing season. you can find them in
meadows, prairies, savannas, agricultural landscapes, gardens, wetlands, and parks
parks in urban habitats.
They are most diverse in temperate and montane areas
as opposed to warmer climates. In Wisconsin, bumble bees are active starting
in early to mid April through October
with some variation between species. They
are very hairy and don't do well in
extreme heat so on hot days they are
mostly active early and late in the day.
Bumble bees feed on nectar and pollen.
They are unique in that they perform
buzz pollination on flowers. This means
they vibrate their flight muscles while
on or in a flower, and the vibrations
release pollen.
In most of our species, females have a specialized structure
called a corbicula on the hindlegs. It is a wide, smooth surface surrounded by
long hairs. When they collect pollen from a flower, it settles into the hair
on their bodies and they groom
themselves and push the pollen onto
their corbicula. In this photo, the bee is carrying a large amount of orange pollen
on her corbicula.
As mentioned bumble
bee colonies are annual with only the
newly produced queens called gynes
surviving over the winter to create new
colonies.
In the spring, the queens emerge from underground hibernation and
begin searching for a nest site as you
see at the top of the diagram. Nest
sites are usually underground for
instance an abandoned rodent burrow
but some species prefer to nest
above-ground. The Queen feeds on nectar
and once she has selected a nest site
she collects pollen in order to feed her
future colony. Once she has stored enough food, she lays eggs, which will develop into
into the colony’s worker bees; workers are always female.
Once the first brood of daughters has
emerged as seen at the bottom of the
diagram they begin to forage for the
colony and the Queen devotes herself to
egg-laying. Successful colonies grow over
the course of the summer with more and
more workers being produced. In late
summer or early fall the colony begins
producing males and new queens, called gynes. Worker bees and old queens die,
and the new queens and males leave the colony to mate.
Once a queen has mated,
she stores the sperm and hibernates. The males die and the new queens emerge in
the spring and the cycle repeats itself.
Bumble bee nests are social colonies
founded by a single queen. As covered in the previous slide, they last only a
single season. Nests can have 100 to 400 workers, or perhaps more.
Nests are often found in abandoned rodent burrows, under logs, or in tufts of
grass. Sometimes bumble bees even nest in
artificial structures like a birdhouse
or a crevice in a wall.
Very little is known
about where bumble bee queens
overwinter. It is believed they burrow a
few inches underground beneath the leaf
layer which eventually gets covered with
snow. Overwintering bumble bees are seldom found. This photo shows a rare exception.
A university employee taking soil cores
for an unrelated project pulled up
up an overwintering rusty patched queen, to his great surprise!
Cuckoo bumble bees have a different life
history strategy than what we have
discussed so far. They are nest parasite, meaning that they invade the nests of
bumblebees of other species and lay
their eggs in them; the eggs are then
reared by the worker bees from that nest. Because their young are cared for and
raised by other species cuckoo bumble
bees do not have to collect and carry
pollen back to a nest. So, they do not have a corbicula on the hindleg. This
is a good way to tell them apart from other bumble bees. In Wisconsin, we have
five species of cuckoo bumblebees but
only three of them have been found
recently in the state. It is possible the other 2 cuckoo species are no longer
found in Wisconsin. But you never know; perhaps a Bumble Bee Brigade volunteer
monitoring!
Because cuckoo bumble bees are
nest parasites occasionally some people
view them in a negative light but we are
equally concerned with monitoring and
protecting all our native bumblebees
including cuckoos.  A healthy host
population
can withstand and support the presence
of cuckoos in the area. This concludes
the training video on bumble bee biology.
If you are new to the project please be
sure to watch all the training videos.
