Photograph of winter garden in snow.

Where Do Native Bees Go In Winter?

Excerpted from: Bees & Bloom

Bee in winter

Ever wondered where native bees go in the winter?

There are many different strategies for surviving the cold months! We’ll take a look at the winter survival strategies of native bumblebees, and solitary bees.

Understanding the habitat requirements of Wisconsin's native bees will be of utmost importance since, as we now know, promoting bee species diversity is critical as native bees are needed for effective pollination of both crops and wild plants and they are under decline.

  Quick Summary

  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.
  Non-native 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.

  Why Do Bees Hibernate In Winter?

In Wisconsin's cold climate, 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.

Dead plant stems, bark, cane, leaves and especially undisturbed soil are the secret winter homes of Wisconsin's solitary bees.

  Native Bumblebees

Exposed bumblebee nest
Exposed Bumblebee Nest

Bumblebees are the only colony-dwelling bees in Wisconsin. 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.

Emergence In Spring

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 starts a successful colony are slim!

Finding An Overwintering Site

Exposed Overwintering Adult Bumblebee
Overwintering Adult Bumblebee

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.

Climate Change And Overwintering

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.

  Solitary Bees

Leafcutter bee flying to nest with cut leaf
Solitary Leafcutter Bee
Returning To Nest

Most bees in Wisconsin 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!).

The female solitary native bee will work through an active season, 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

Overwintering Young Solitary Bees

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.

Bees active in earlier spring, like 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, like 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.

Solitary Bee Overwintering Nests - Gardeners Beware!

Some solitary bees are very tiny and may overwinter in hollow plant stems – something you should be aware of! As you begin to tidy up your garden for the winter - especially if they are thinking of burning or removing the plant stems, you may be destroying solitary bee nests.

  Helping Pollinators To Overwinter

Bee House With Larvae

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.

Dead plant stems, 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 a website that provides several different plans for do-it-yourself native bee habitat, Creating Solitary Bee Habitat that works well for native bees. 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!

Bumble bee with pollen grains

Benefits of Pollen to Bees

The bee's basic nutritional requirements are similar to those of humans; they need proteins, carbohydrates, minerals, fats/lipids, vitamins, and water. Learn More!

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Bee Quiz

Take this quick quiz and see how much you know about bees—our favorite essential pollinators working around the world. This quiz is intended for fun, in a random-facts-can-be-cool kind of way.

Shooting Star plant

Spring Pollinator Plants

Spring begins andhungry pollinators are on the wing, looking for food. From the moment emerge in spring to the time that they hibernate or migrate in the fall, pollinators need to eat.

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