Helping bumblebees

I am particularly fond of bumblebees, partly because they look like insect teddy bears. For years, they’ve been welcome company while I work in my garden.

Bumblebees are also native bees. They are a bit like honey bees because they live communally, but their nests contain fewer numbers (hundreds, not thousands). They usually nest underground or at ground-level, such as in old mice nests. They may also use above-ground cavities in trees or bird houses.

Bumblebee life cycle

In spring, hungry queen bumblebees emerge from their underground hiding-spots to fatten up and search for a nest site. If you see a big bumblebee early in the spring, it is a queen. They need early, spring blooming flowers that provide both pollen and nectar. Native, woodland flowers are especially good choices, as are flowering shrubs and trees; I add a few more to my garden each year. If a bumblebee queen has a poor start in spring, it jeopardizes the success of her nest throughout the summer, and reduces the likelihood of a new generation of queens for next spring.

Queen bumblebees are very picky about their nest location. I have watched them explore the periphery of our yard, popping into an occupied chipmunk burrow, a vacant groundhog den, and various other holes. It is actually hard to find bumblebee nests, and I have never seen one. (In fact, they are so difficult to find that it makes it hard to know what kind of habitat to create for bumblebees. A York University study is soliciting help from the public to submit photos and videos of bumblebee nest sightings to help learn more about them.)

Once a queen chooses a nesting spot, she gathers pollen and lays eggs on it. She also builds and fills a little honeypot, so she can eat while she sits on her egg, like a chicken! She stays in the nest shivering to keep the eggs warm. This early bumblebee nest phase takes a few weeks. Every year, I worry and complain that I’m not seeing bumblebees in the late spring. Now I know why.

Once the worker bumblebees emerge, they take over the foraging duties and the queen spends the rest of her life in the nest laying eggs, and helping care for her offspring. It is relatively easy to provide flowers for bumblebees because they are generalist foragers, meaning that they will visit a wide range of flowers for pollen and nectar. Therefore, you will find lots of bumblebees in city gardens.

Sadly, in the fall most of the bumblebees die, except for new, mated queens. These queens leave the nest and burrow under leaves or underground to wait for spring. It is important to provide lots of fall flowers, especially asters and goldenrods, so queens can build up stores to last them all winter in their dormant state. To help queen bumblebees overwinter successfully, keep leaf litter on the ground during fall and early spring.

For photo of a queen bumblebees sitting on her eggs, next to a honeypot, see Queen Bumble Bees Fly Solo in the Spring. One of the most interesting books I’ve read about bumblebees is Bumblebee Economics, an older title by Bernd Heinrich, which is available at the Ottawa Public Library.

The UK Bumblebee Conservation Trust has some good photos of bumblebee nests. The founder of this organization, Dave Goulson, has written some great books about bumblebees and their plight in the UK: A Buzz in the Meadow, and A Sting in the Tale are also at the Ottawa Public Library.

You can find instructions online for building bumblebee boxes, but outside of captivity in a greenhouse, they rarely use them.

Identifying bumblebees

There are many types of bumblebees and they can be difficult to distinguish from one another. I have many Common Eastern bumblebees in my garden, and have seen a few other types as well. Pay attention to a bumblebee’s stripes, the back of its head, and face (if you can see it well enough or take a photo) to try to identify it.

Wildlife Preservation Canada offers a handy, free poster that illustrates common Bumblebees of Southern Ontario as well as the Bumblebees of South-Central Ontario PDF. For more detailed information for identifying bumblebees, consult the Bumblebees of the Eastern United States PDF from the USDA Forestry Service and the Pollinator Partnership. You can also add sightings on Bumble Bee Watch by taking photos and submitting them for ID confirmation.