The Bumble Bee Life Cycle

Bombus lucorum - white-tailed bumble bee queen on knapweed.

The bumble bee life cycle starts with an impregnated queen, when she emerges from her nest from her winter snooze. 

In order to prepare herself for leaving her cosy hibernation hole, the young queen bumble bee has to first do a little ’warm up’ – just as you or I may do our own little ‘warm up’ routine before going for a winter jog. To do this, she vibrates her flight muscles very fast to generate heat, and when ready, she’ll then take off to look for pollen and nectar.

Bombus hypnorum - tree bumble bee queen (dark form) - foraging on bramble.Bombus hypnorum queen (dark form) - foraging on bramble.

Depending on the species, some of these queen bumble bees will appear in the spring the following year, from March onwards. However, some species may appear as early as February. 

For the queen bumble bee, this is a very vulnerable time. Pollen and nectar sources are scarce, and she’ll need to find both very quickly in order to sustain her during these crucial days. The nectar gives her energy whilst the pollen helps her to replace vital body fats. It also provides protein to help her ovaries mature, and is needed later to feed her brood.

Bombus lapidarius red-tailed bumble bee queen on aster - Stokesia.Bombus lapidarius red-tailed bumble bee queen on aster - Stokesia.

During this time, plants such as mahonia, pussy willow, crocuses, rosemary, winter heathers, blackthorn, pussy willow, berberis and daffodils provide a vital life line for bumble bees.

Once the queen bumble bee has recovered, her next task is to find a suitable place to nest.

An abandoned rodent hole, tussocky grass, or even a bird nest box can provide a suitable home, depending on the species.

Bumble bee nest.Site of a bumble bee nest - highlighted by the pink circle, a bumble bee entering the nest.

Again, depending on the species, there are slight differences in the way broods are reared, however, a general description is as follows:

Once the nest site has been located, the queen bumble bee will build a little wax cup inside it, which she will fill with nectar to sustain her whilst she incubates her eggs. She’ll also create a further wax cell, in which she will deposit a mound of pollen, and then lay her eggs on top of it. She incubates the eggs by lying on top of them, and again, by vibrating her flight muscles to generate heat up 30 °C!

After about 4 days, the eggs hatch into larvae (these look a little like maggots).

The larvae continue to feed and develop, and will go through a number of stages in development (shedding their skin 3 times) until after about 14 days, they produce silken cocoons and pupate. Within the pupae, the larvae shed their skin once more, and undergo metamorphosis. After about 14 days, the little grub-like larvae are transformed into a young bumblebees, which bite their way out of their cocoons.

Bumble bee colony.Bumble bee colony.

The first bees to emerge from these cocoons are young female worker bees.

Meanwhile, the queen has already laid more eggs that are also in development.

The newly emerged workers will be a great help to the queen in rearing the rest of the brood.

Within a day or two, these workers will set about helping the queen, initially with nest duties, but some will then go out to forage for pollen and nectar for rearing the next brood (usually more workers). A colony of bumblebees could have between 50 – 500 workers, but will commonly consist of around 120 to 200. 

At some point, the queen will stop producing workers, and will switch to rearing males and young queens.

Once the males have emerged, they will soon leave the nest in search of mating opportunities.

Buff-tailed bumble bee queen on Oregano (Marjoram).Buff-tailed bumble bee queen on Oregano (Marjoram).

The young queens may remain in the nest for a while, laying down fat reserves in preparation for the winter hibernation.

All being well, a honey bee colony should survive the winter. 

In the case of bumble bees, the whole colony will die, apart from the new queens.  The new queens leave the nest, mate, then hibernate, and re-emerge the following year to establish new colonies of their own. And so the next generation of bumble bees begins.

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Providing Habitat For Bumble Bees

It is a good idea to provide plenty of foraging opportunities, with an abundance of flowers over a long season.

Take a look at my lists of plants for bees.

Fill your garden with flowers for bees if you can.Fill your garden with flowers for bees if you can.

You may wish to consider providing artificial nest sites for bumble bees. You can do this by purchasing one, however, success is far from guaranteed, and indeed, you may have more success with a previously used bird box, or an upturned plant pot under the garden shed.  Some bumble bees like to make their nests in compost bins.

Bumble bee nest in a bird house.Bumble bee nest in a bird house.

My personal recommendation is don't try to force a bumble bee to nest in a 'bee house' you have purchased, instead, allow nature to take its natural course.  If you have purchased a bee house, it may or may not be suitable or in the ideal location, and there are other factors to be considered, such as abundance of the correct flower types, nest conditions.


You might like these

  • Do Bumble Bees Make Honey?

    Bumble bees store nectar in little wax pots for feeding the colony as it grows, but it is not really quite the same thing as honey made by honey bees.

  • Should Bumble Bee Be Written As One Word Or Two?

    A look at the rationale for writing bumble bee as two words rather than one (bumble bee instead of bumblebee).

  • Bumble Bee Nests

    Bumblebee nests: all about them, what to do if you find one, and what to do if you need to move one.

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