Saturday 25 November 2017

Bumblebees begin to emerge from hibernation

By Jim Hurley - Nature Trail

Any day now, at least in the extreme south of the country, we should see the first bumblebee emerge from winter hibernation heralding the arrival of spring. In the cooler far north they will, of course, emerge later as spring is slower to arrive.

We have twenty species of bumblebee in Ireland and one of the first to emerge each year is the Buff-tailed Bumblebee so named for obvious reasons. In addition to emerging early the Buff-tailed Bumblebee is our largest and commonest bee.

Those emerging are all females. Last autumn the young queens mated with male bumblebees and all of the males and the workers died with the onset of autumn leaving the fertilised queens to survive the winter and perpetuate the species into the following year.

A hibernating queen might have survived the winter in an abandoned mouse hole or other hideaway place underground. She now emerges hungry to feed and ready to start a new colony. Flowers are scarce at this time of year so gardens are important refuges and sources of food with their early-flowing shrubs and blooms. In the wild, Dandelions are an important food source.

Once fed, the queen turns her attention to establishing a nest, laying eggs and tending them to produce the first batch of workers. The workers will not be on the wing until next April and will be identified by their smaller size and their white tails. While the species is named 'buff-tailed' only the queens have a buff-coloured rear end; males and workers are white rather than buff.

Workers are infertile females. Their sole purpose in life is to tend the queen and rear her offspring: they play no role in reproducing the species. As summer approaches the queen produces fertile offspring, both males and females. These reproduce and the cycle starts over again producing a second generation, a generation of summer queens that doesn't need to hibernate.

The summer queens continue the cycle and autumn queens arrive before the onset of winter. Two generations used to be the norm in the past but with climate change, warmer towns and cities and winter-flowering shrubs in parks and people's gardens there is emerging evidence that the Buff-tailed Bumblebee is evolving to fit in a third annual generation in many areas.

Bumblebees do sting but it's only the larger females that do so; neither the smaller males nor the sterile workers sting so they are safe to handle gently.

Wexford People

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