Where Do Bees Go In Winter?
Ever wondered where bees go in the winter? With over 20,000 species of bee worldwide, there are so many
different strategies for surviving the cold months! We’ll take a look at the winter survival strategies of native
bumblebees, and native solitary bees.
Of the thousands of bee species in North America, none have the same habitat requirements as their distant
European cousin, the Honey Bee, and our native bees often get “left out in the cold”. Understanding North
American bees will be of utmost importance since as we now know, promoting bee species diversity is critical for
effective pollination of both crops and wild plants.
Differences aside, all bees in North America must somehow account for the time of year when there are no flowers
in bloom. Winter is a treacherous and resource-scarce period for many animals, and the diverse ways different
bees handle these challenges is a true representation of the ‘ingenious’ hand of natural selection.
Just like with people, we should be celebrating diversity with bees. Each species is a very important piece of the
puzzle that is ecosystem stability. Understanding their life cycles, and how they make it through the most
tumultuous time of year is just one step toward improving local habitat for these essential critters. Lest we
forget, excluding those introduced to the continent by us, most bees have a much longer history with this land
than any human!
★ Bumble Bee queens hibernate in winter.
★ Most solitary bee species will overwinter in a birth
cell, either as new, fully developed adults not yet emerged from their cells, or as pupae, waiting to complete their
development.
★ Honey bees overwinter in their hive or nest, forming
a winter cluster around the queen, with the colony itself much reduced in size. They are less active though not
entirely dormant, and the cluster 'shivers' to keep warm.
In our cold climate (rather than exotic locations) where there are no flowers from which to feed in the winter,
bees need to shelter from the weather and conserve their energy until the flowers are blooming again.
The most common form of over-wintering in bees involves either a pre-pupa or a fully developed,
non-emerged adult within the birth cell.
The closest native relative to the honeybee, bumblebees are the only colony-dwelling bees in North America.
Colonies are comprised of much fewer individuals, thus, the species in this genus have their best shot for
survival by being ‘annuals’. As autumn approaches, fewer species of bumblebee are seen foraging. The
natural lifecycle of bumblebees means that most of the colony will die, and only the new bumblebee queens will
survive. They will mate with the males, and importantly, feed to build up fat reserves ready for their winter
snooze (hibernation). The mated queens will hibernate through the winter underground as the only surviving
individuals from their parent colony.
The lucky queens who hibernate successfully without disturbance will emerge from their burrows when spring
temperatures signal it is time for them to start a colony of their own. The season of the queen begins with
searching for an optimal nesting site while visiting flowers to sip nectar for energy. Nesting sites for bumblebees
are scarce, and even if a queen finds a suitable site, the chances that she start a successful colony are slim!
After locating a suitable site, she must play both queen and worker, starting the risky business of leaving the
nest untended in order to forage for the few young she can produce on her own. If a queen makes it past this
stage, she can stay inside the nest and focus on laying eggs while her daughters (the workers) take care of the
rest of the work until winter rears its cruel head once more.
Are changes in climate affecting hibernating patterns of bumblebees - such that we even witness winter active
bumblebees? In milder climates – and even in milder weather zones of countries such as the UK, bumblebees
have been known to remain active through the winter. If winters are getting warmer, perhaps this should not
surprise us.
Most bees in North America are solitary. During the warm season, a single, mated female will tend a nest in a
tunnel. Depending on the species, the tunnel may be in a network underground, or in an abandoned hole off the
ground left behind by beetles, woodpeckers, or even humans (check it out!). She will work through an active
season of a bit over a month until her death, leaving behind several offspring with enough food to help them
develop properly through the rest of the warm season
Depending on the timing of the adult’s active season, the young left behind will overwinter as fully formed adults
in their cocoons, or as diapause larvae, waiting to pupate until spring. Essentially, bees active in earlier
spring (e.g., mason bees) will have ample time to pupate in the summer and will overwinter as hibernating adults
in their cocoons. The young left behind by bees active in the summer (e.g., leafcutter bees) will have less time to
develop, and will overwinter as hibernating larvae. Either way, these bees will emerge out of their burrows at the
same active time as their parents the year before and will begin the process again.
Some solitary bees are very tiny and may overwinter in hollow plant stems – something wea are keen to remind
gardeners of, as they begin to tidy up for the winter - especially if they are thinking of burning or removing
the plant stems!
If you are one of those gardeners who has felt inferior to your neighbors who fastidiously clean up every shred
of plant debris and till the soil in November to be ready for spring, it’s time to stand tall and proud for having a
“messy” garden. Old bark, cane, leaves and especially undisturbed soil are the secret winter homes of
pollinators. Some have gorged like bears to make it through the winter; others wait in suspended animation as
larvae, pupae or eggs.
So, now that you know how many species are counting on you to leave soil undisturbed, piles of leaves
untouched, and shrubbery unpruned over winter, you can feel good about being the untidy gardener! And if
you’d like to fashion some homes for bees, that’s entirely possible. Here’s one
BEE HOUSE PLAN that works well for the 30 percent
of native bees that live in tunnels. A myriad of others are available; to see their diversity and artistry, check out
“native pollinator houses” and click on “images”. It’s also possible to make butterfly and bat houses, and winter
is a great time for woodworking projects!
☆ Wisconsin Bee Identification Guide
☆ Spring Wild Bees of Wisconsin
☆ Bumble Bees of Wisconsin
☆ Wild Native Bee Nest Boxes