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Check out my book, The Sustainable-Enough Garden, available on Amazon, and the book's web site at www.thesustainable-enoughgarden.com. See more plant photos on Instagram.

Sunday, May 26, 2019

A mother's work is never done

I felt I had a personal encounter this week with the biggest bumblebee I’ve ever seen. Maybe I’m wrong, but I seemed to spot the same rotund, furry bee visiting flowers near the house several times in the course of a sunny afternoon. 

    Perusing Heather Holm’s Pollinators of Native Plants, I learned that the bee I was watching was probably a queen looking for pollen and nectar for her offspring. 


Earth bumblebee (Bombus terrestris)-photo Ivar Leidus

Bumblebee queens can be three times as large as worker bumblebees. The orange ball I saw on one of her back legs was probably her corbicula, or pollen pouch. When I watched her moving from flower to flower, she was collecting pollen grains on her head, thorax and abdomen, combining them with nectar, and storing the mixture in the pouch to carry back to her nest.

The orange ball is her pollen pouch-photo Tony Wills

    Another bee behavior I’d happened to notice also made sense now. A few days before, I saw a bumblebee fly into a small hole in the mound of sheet compost I started last month. The mound is topped with chopped straw and hay over a layer of compost; under that there’s a thick pile of wood chips. Now I know that this could be an appealing spot for a bumblebee queen looking for a place to dig a ground nest. 


The top of the sheet compost offers a good bee nesting site

    Bumblebees can sting repeatedly without dying, but none has ever threatened me. The ones you see sleeping in flowers in the early morning are probably males, because once they leave home, they don’t have a nest to go back to.


    I learned that except for rising queens, all bumblebees die at the end of autumn. A queen spends the winter underground, emerging early next spring to start her colony. 


Bumblebee on a crocus-photo Rasbak

She looks for a hole that another animal has made in the past or for some loose, open sandy or loamy soil where she can dig tunnels. Sandy loam is what I’ve got, but I tend to cover open soil with mulch. In future, I’ll make a point of leaving some unmulched areas for bee nesting sites. Meanwhile, the loose, uncompacted surface of the sheet compost mound is providing nesting opportunities.

    I’d thought bumblebees were solitary, but they live in eusocial colonies, where mothers and daughters work together to raise the next generation. With the results of her foraging, my queen will create nectar pots and pollen balls, lay her eggs, and seal each one in wax with some food for the larva when it hatches. When the larvae pupate and emerge as adult bees, those tapped to be next year’s queens will get more food and grow bigger. How does the queen decide which of her daughters will succeed her?



    Bumblebees are generalist pollinators: they visit many kinds of flowers, in contrast to some other native bee species that specialize on a few kinds of flowers. That’s why bumblebees are so useful to farms and gardens and why it makes sense to protect them by providing habitat and eschewing pesticides.


It's not hard for bees to find flowers in the garden in May. August will be more of a challenge.

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