by Watershed Stewardship Assistant, Rachel Morris
I am a self-professed winter lover. I love snow, I love the cold, and I love seeing the moon every night at 6PM. But I know short days and chilly weather can start to drag, and when February rolls around, I start to feel myself looking forward to spring. To me, nothing feels like spring as much as seeing the very first insects of the year: bumble bees! Once the bumble bees are out, I know that the spring flowers are blooming, temperatures are above freezing, and summer is on its way.
Read on to learn about what our local bumble bees are doing during winter, and what they’ll get up to in the spring!
WINTER
Diapause (Too cold, life’s on hold)
Many insects spend winter in their larval or egg stages, pausing their development through freezing weather—but not queen bees! Bumble bee queens instead overwinter as adults, earning a head start on pollination as soon as spring hits. Soon afterwards, they’ll be ready to find a site for a nest and start creating workers.
As the weather cooled off last summer, fall bumble bee queens foraged as much pollen and nectar as they could, building up their fat stores. Once it started feeling frosty, the queens started looking for the perfect patch of soil: sheltered by overhanging vegetation, but still loose and diggable. Once they found a good spot, they burrowed underground and dug out a little hollow in which to spend the winter. They then entered diapause, a hibernation-like state where metabolism slows to about 5% of its active rate. Right now, bumblebee queens are between 2-15cm underground, waiting out the winter. They could be under your rosebush, in the leaf litter at the base of a tall tree, or nestled in a carpet of moss under a brush pile.
The full bumble bee life cycle, beginning at the top with a queen (the largest bee in the diagram) establishing her nest. In early summer, she incubates her larvae and forages. In mid summer, she incubates her eggs, and her workers (shown by the smaller bees) forage. In late summer/fall, she lays eggs that hatch into reproductive females (fall queens) and males, who mate with individuals from other hives. In winter, the mated fall queens spend the season underground in a reduced metabolic state called diapause. Image created by Jeremy Hemberger https://jhemberger.github.io/graphic_art/
“Insect diapause is a lot like hibernation, but there are some differences. The main difference is that mammals remain active until winter is well established and temperatures are frigid, but insects that enter diapause become dormant in the autumn well before it gets too cold for them to function. Another difference is that mammals can sometimes rouse themselves for short periods of activity during the winter, but once an insect enters diapause it will remain dormant until spring even though the weather might be suitable for normal growth and development.”
SPRING
Emergence (and finding your own bee’s nest)
In late April or early May, the first bumble bees you will see will be big, fat, and fuzzy. These are the spring queens, freshly emerged from their overwintering sites. Consistent soil warming in the spring will prompt each queen to wake up, dig her way back out, and start hunting for her first meal of the year: pollen and nectar. She’ll flock to reliable early wildflowers, such as prairie pasque flowers and phlox, and flowering shrubs like saskatoon and thorny buffaloberry. If you have an apple tree in your yard, you may recall seeing and even hearing enormous bees drone around the blooms in the springtime. They are gathering pollen and nectar, eating their fill after a long winter, and pollinating the flowers in the process.
This Hunt’s bumble bee queen (Bombus huntii) was spotted in May. She had recently emerged from hibernation and was foraging on early-blooming golden buffalo bean. Photo by Shannon Hart.
However, spring queens have more to do than just forage. In a park, woodland, or open prairie on a spring day, you will see bumble bee queens flying back and forth, low to the ground. They are nest searching! Queens put time and effort into finding the perfect spot for their nests. Unlike their winter hibernaculum, this is not a hole the queen will dig herself. She’ll take advantage of a rodent’s burrow, a hole in the ground, or a nook under a brush pile. If you keep an eye out this spring, you will certainly see and hear a queen or two flying in quick, low-to-the-ground zigzags.
Once they find the perfect spot, queens will establish a nest. They will lay eggs that they’ve been harboring all winter. These will hatch into larvae, then turn into pupae, then become fully-fledged worker bees. At first, the queen does all the foraging herself, bringing nutritious pollen and nectar back to the nest. Once they reach maturity, the workers will take over the duties of foraging, guarding the nest, and even caring for the young, and the queen will lay and incubate eggs full-time.
SUMMER
Workers (and the bee’s knees)
Once summer has kicked into high gear, around June and July, you will see very small bumblebees in your garden or when you’re out on walks. If you get a close look, you may notice that their back legs have yellow bulges close to their knees. These bees are workers, carrying pollen home to their nest in special ‘baskets’ called corbiculae.
A red-belted bumble bee (Bombus rufocinctus) worker foraging pollen. Workers are smaller than queens and, although female, lack reproductive capacity. Photo by Rachel Morris.
A tri-coloured bumble bee (Bombus ternarius) with a full pollen basket. The lump of pale yellow on her back leg isn’t part of the flower: it’s pollen she has gathered and stored in a specialized pollen-carrying structure called a ‘corbicula’. There is one on each of her back legs! Photo by Ken Orich.
FALL
Reproductive offspring (and flower naps)
A male tri-coloured bumble bee (Bombus ternarius). Male bumble bees are smaller than queens, although they have an additional abdominal segment (7 rather than 6). They have narrower legs as they do not have pollen-carrying baskets. They also lack stingers. Photo by Ken Orich.
In August or September, depending on the species, you will once again start seeing and hearing surprisingly large bumble bees on flowers near you. These are new queens, one of the first signs that fall is on its way. Bumble bee nests will start generating reproductive females (fall queens, also called ‘gynes’) and males (also called ‘drones’) around the same time.
When fall queens and males reach maturity, they will leave the nest to seek out and mate with bees from other nests. Fall queens will continue to visit their original nest for protection and shared resources, although males will not. Male bees can often be seen sleeping in flowers or on vegetation in the late summer.
End of a nest’s lifespan (and passing the crown)
After a nest of bumble bees has created mature reproductive offspring, the nest activity will slow down through the fall until the original queen and workers die. Only the fall queens, who have mated with neighbouring males and are ready to start a new nest in the spring, will survive the winter. They spend the fall foraging on crucial late-blooming flowers to build up their fat stores for their diapause. Once spring comes, they will start the cycle all over again.
OWC field staff spotted this fall queen (northern amber bumble bee, Bombus borealis) at Chain Lakes in August of 2024! She is wasting no time in getting ready for winter: you can see her tongue sipping nectar from this red clover. Photo by Maria Albuquerque.
What about honey bees?
The bumble bee life cycle is different from their cousins, the honey bees, because the bumble bee nest is annual (lasting only one year), and the honey bee nest is perennial (lasting multiple years). Honey bee colonies overwinter as a whole, including the queen and workers. They eat their stored up honey reserves to survive. Bumble bees do not make or store large quantities of honey (they make a little, for rainy days), because they do not need to feed a whole colony for the winter. The overwintering bumble bee queens survive thanks to their insulation under the ground and their bodies’ built-up energy reserves. Honey bees, although an important domestic animal, are not native to North America.
UNTIL SPRING RETURNS!
I know I’ll be keeping an eye out for bumble bees once April hits. In the meantime, enjoy the snow and the lengthening days, and remember that summer—and all of our animal friends—will re-emerge again.
Further reading about bumble bees and their life cycle:
Bumble Bees of Southern Alberta: An Identification Guide to Queens. Government of Alberta.
https://www1.agric.gov.ab.ca/$Department/deptdocs.nsf/all/prm13779/$FILE/bombus_guide.pdfLife cycle and biology. Bumble Bees of Wisconsin. https://wisconsinbumblebees.entomology.wisc.edu/about-bumble-bees/life-cycle-and-development/
Bumble Bees: Nesting and Overwintering. Xerces Society. https://xerces.org/bumble-bees/nesting-overwintering
Native Pollinators and Agriculture in Canada. Government of Canada. https://publications.gc.ca/collections/collection_2014/aac-aafc/A59-12-2014-eng.pdf
Liczner, A.R., Colla, S.R. A systematic review of the nesting and overwintering habitat of bumble bees globally. J Insect Conserv 23, 787–801 (2019). https://doi.org/10.1007/s10841-019-00173-7, also available at: https://drive.google.com/file/d/1bvOoZ-tMRuLWkqNH1IfF6LVLeTJyfY6j/view
How insects prepare for winter. Scientific American. https://www.scientificamerican.com/blog/observations/how-insects-prepare-for-winter/
This work is part of a project that is financially supported in part by the Government of Canada’s Habitat Stewardship Fund for Terrestrial Species at Risk.
Banner image: “Dreaming of crocuses.” Original watercolour by Rachel Morris, 2025.
