Bumblebee Season Finale

Bracketing the walkway to our front door, is a small collection of domesticated flora with showy blooms. Warm temperatures allowed these plants to thrive well into November. They continued to produce new flowers long after the blooms on native plants and disappeared. During the latter half of October, swarms of bumblebees moved in and made these plants home.

Things went well for the bumblebees until the overnight low temperature hit 26° F. Coleus, which I had allowed to flower and which turned out to be a favorite of the bumblebees, froze and was lost as a nectar source. A low of 19° F the next night put an end to the salvia and most of the zinnias.

That low temperature also proved to be too much for most of the bumblebees. The patio was littered with bodies Sunday morning. Bumblebees have the ability to warm their bodies by shivering, so they can survive some cold temperatures. Eventually, the temperatures get too cold or the bee just runs out of energy and it dies.

Most of the bodies had the classic tongue extended death repose. A check of the bodies show the bees all to be male. Bumblebee colonies are single-season affairs. The colony begins in the spring when a single fertile queen begins laying eggs and raising her brood. Near the end of summer, young queens and males leave the soon to collapse colony. The males spend their time drinking nectar and searching for queen bees with which to mate. Eventually, the queens hide themselves away in a safe place to spend the winter and the males are left with nothing to do but drink nectar and await the killing freeze.

The few bees that were left alive Sunday morning were found hanging from the flowers. They were all on the porch side of the flower planting where a little bit of warmth stored in the concrete and brick gave them a slight survival advantage. It’s typical behavior for these bees to just stop their activities as evenings begin to cool and spend the night on the flowers from which they were feeding.

When temperatures warm up, the bumblebees once again become active and continue feeding from where they left off the day before.  A temperature of 21° F Sunday night left no bees alive Monday morning.

As this video shows, after a cold night it takes the bees a little while to regain their coordination and function normally.