Ottawa cousins of Toronto’s unofficial bee

When I began learning about native bees two years ago, I was delighted to find the PDF book, Bees of Toronto. There aren’t many Ontario-specific resources, let alone ones from Ottawa. Now we’re lucky to have the Wild Pollinator Partners blog posts and events that highlight native bees in our area.

After reading Bees of Toronto, two things stuck with me:

  • the forward is written by Margaret Atwood, whose father was an entomologist. As an Atwood fan, I am pleased that in addition to knitting, we also share an interest in pollinator gardening.
  • Toronto has an (un)official bee, bicoloured Agapostemon, that lives in subterranean ‘apartment buildings’; while females each have their own ground nest networks, they share an entrance. This shared entrance allows bees to take turns guarding it from intruders, while their neighbours are out foraging.
Page 22 of the Bees of Toronto PDF…
…and page 23.

For more on Toronto’s efforts to create good, urban habitat for pollinators, listen to the PolliNation Podcast interview with Scott MacIvor. I hope these unique pollinator initiatives survive the Ford government, which is degrading Ontario’s protections of wild spaces and wildlife, and is targeting Toronto’s progressive ways.

Meet the Ottawa relatives

This week, while I was supposed to be weeding the garden for upcoming tours, I came across a peculiar ground nest beside the driveway. I have never seen anything like it before, and I immediately worried that I had ground-nesting wasps next to a busy walkway. The nest is conical with two ‘chimneys’. After some research, I concluded the structure didn’t look like as wasp nest.

Strange nest with ‘chimneys’. (June 24, 2019)

I camped out on the uncomfortable asphalt to observe. The weeds could wait because I had more important investigative work to do. Whatever was in there would appear, but pop down out of sight whenever I got close. Strangely, and a bit disturbingly, smart.

Insects peeking out. (June 24, 2019)

After I was still, they began flying out — five of them in total. Here’s a brief Youtube video of them exiting the nest. I could see pollen on their legs, which confirmed that they’re bees (vegetarian) and not wasps (which eat other insects, and nectar). Also, they’re a very pretty green on top, with striped abdomens. Aha! They are bicoloured Agapostemon, also known as green sweat bees.

I have seen green sweat bees go into ground nests before, but only singly. The nests were just holes in the ground, never into such a strange-looking structure. I wonder if the conical shape of the nest indicates that there are a lot of females excavating below. I also wonder if they would all be sisters, or if any female green sweat bee in the vacinity could move in.

If you have a sharp eye, you can see one of the reasons the green sweat bees are on guard. Sitting on a leaf in the lower-right, you’ll see a kleptoparasitic bee lurking, waiting for an opportunity to invade their nest to lay its own eggs.

A close-up of the kleptoparasitic bee. (June 24, 2019)

Green sweat bee flower favourites

Well, the next question was: where were they finding all this pollen? They were making quick trips with significant pollen loads on their back legs. After looking all around the front and back gardens, and my neighbours garden, I found green sweat bees on prairie cinquefoil growing nearby. I grew this from seed last year and have never seen it bloom before. The flowers look a lot like strawberry flowers.

A green sweat bee collecting pollen inside a prairie cinquefoil flower. (June 24, 2019)

In Bumblebee Economics, Berndt Heinrich chose prairie cinquefoil as one of the plants for tracking pollen-collection visits of different bumblebee species (page 154). Other flowers included wild carrot (non-native), St. John’s wort, pond lily, and wild rose. I figured that these plants must be good pollen-producers, so I added them to my garden. The wild carrot (Queen Anne’s lace) was already in my yard and has been hard to eliminate because it self-seeds so prolifically.

From previous years, I know that green sweat bees also really like red pincushion flower (Knautia macedonica). This plant short-lived but self-seeds moderately, so there are lots of flowers around. I’ve grown red pincushion flower for years because it blooms for months, and I like the dark red colour of the flower buttons.

Green sweat bee on a red pincushion flower. (June 25, 2019)

Like I always say, you never know what you’ll see in the garden. Back to weeding.

Oh, wait — there are the Chickadee parents with their 5 babies. I can’t miss watching that. The weeding can wait, again.

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