Green Metallic Bees In My Toronto Flower Garden
One gloriously sunny morning this past summer, I was taking my time in the garden with teacup in hand. That was soon replaced by my camera when I spotted some interesting insects on the False Sunflowers (Heliopsis helianthoides “Ballerina”). One such bug that I had never noticed before was this Virescent Green Metallic Bee (Agapostemon virescens) of the Halictid Family.
A sudden breeze tousled the flowers in my garden every so often, which made it challenging to capture photographs of the various insects since they were on the bobbing heads, but I was at my leisure and for once had no need to hurry.
Actually, several Virescent Green Metallic Bees were visible on the bright yellow flowerheads. What made them easily recognizable is the bright metallic green on their heads and thoraxes combined with their ringed abdomens. The abdomens are black and ringed with pale stripes owing to either short yellowish erect hairs on a male bee, or white hairs if the bee is a female. I think that this bee is a female.
My garden was abuzz with activity given the warm sunshine and dry conditions, and I soon realized that not all of the Green Metallic Bees were alike. I noticed that this one, for instance, has a solid black abdomen, and after seeking advice from sources more knowledgeable than me in the field of insects, I learned that it is also a female Virescent Green Metallic Bee, albeit one whose stripes are not yet defined.
Virescent Green Metallic Bees are between 3/8-1/2 inch in length (10-12 mm), and their wings are a smoky brown. As I observed this pair of females, they drank nectar with abandon flitting from first one and then to another of the False Sunflowers.
I was quite fascinated with the bees as they crawled around the composite flowerheads. It was apparent that the pollen brushes on the back legs of one bee were fully loaded with pollen. These tufts of hair called scopae gather up pollen as the bees move amongst the stamens of a flower. The pollen is then transported back to the nest for the larvae to eat.
You can tell that this female is on a return trip to the sunflowers because the scopae on the hind tibia are clean. Soon, pollen will collect on the sticky hairs, and she will leave to deposit it in her nest.
Virescent Green Metallic Bees are ground dwellers, preferring dry soil or vertical banks as nest sites. A female who founds a colony will dig a branching burrow system with a small cavity at the end of each branch. With the massive loads of pollen stuck to the outer surfaces of her hind legs, she will return to the nest and deposit a small ball of pollen in each cavity.
A mother bee will stockpile enough pollen in each chamber to nourish one offspring from egg to full size. The pollen is moistened with saliva and nectar and then fashioned into neat little balls or loaves. It is thought that the use of saliva to help bind the pollen and nectar serves to transfer protection to developing larvae against bacteria and fungus infections much as mothers’ first milk in mammals provides temporary protection from diseases. Colostrum, the first milk produced by mammals, is oddly enough, also referred to as Beestings.
Some Agapostemon Bees are solitary, but Virescent Green Metallic Bees are communal. Often, a group of up to 20 females will share a burrow entrance, with each female digging her own tunnel, establishing her own cavities and preparing for her own young. When each cavity is provisioned with pollen loaves, the females will lay one egg in each chamber and seal it up. One bee usually guards the portal to the colony by placing its head level with the soil’s surface, like a plug.
I have since learned that Virescent Green Metallic Bees are most often seen in flower gardens during the mornings of early summer. They not only gather nectar and pollen for the nest but also to nourish themselves. Nectar is a carbohydrate so serves as a high-octane fuel. Pollen is a concentrated energy source that provides energy for flight, colony maintenance and general daily activities.
That morning, the Virescent Green Bees lingered in my backyard garden seeming to favour the False Sunflowers. These bees usually collect pollen from a wide variety of flowers, and a good selection of blooms can be found in my flower garden in July,
so it was no surprise, a couple of days later, that Bob spotted some of these same bees on the Showy Blanket Flowers (Gaillardia pulchella) in my boulevard garden.
I love these vibrant, playful flowers, and they have taken well to the poor and dry soil beneath a Linden Tree. I am pleased because it offers up another option for the bees and other pollinators that are around at this time of the year.
Because Virescent Green Metallic Bees have short tongues, they are limited as to which flowers they can utilize as a source of nectar and pollen. They must visit flowers that offer easy access to these sources of food, but it is quite common for a bee species to prefer the pollen from only one or a few kinds of flowers.
Virescent Green Metallic Bees are found in meadows and gardens across southern Canada. They prefer any location with a good supply of nectar and pollen-rich blooms as well as suitable nesting habitat. Also known as Green Sweat Bees, they are the largest and most beautiful of all North American bees.
It seems that I can expect to see more of these bees as the season marches on. During August and September, the males should be seen swarming around my hedge, hollyhocks and Rose of Sharon. These particular plants serve as a rendezvous point for the males and females during the day, but at night, the males are found sleeping in the blossoms by themselves. C’est la vie!
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