A lone Yellow-banded Bumblebee

On July 31st, armed with my camera, I patrolled the front and back yards. As I always say: “You never know what you’ll see in the garden!” In the backyard mini-meadow, I spotted an unusual-looking bumblebee. I took photos of it and headed inside to identify this new bee.

An unusual bee in the garden.

It appeared to be a Yellow-banded Bumblebee — a rare and declining species. Eager for an expert opinion, I fired off a few emails and submitted photos to Bumble Bee Watch and iNaturalist. Others confirmed that it was a Yellow-banded Bumblebee. If it had a yellow patch at the tip of its abdomen, the ID would be conclusive; however, Yellow-banded Bumblebees don’t always have this distinctive patch. I was very excited about our special bumblebee guest.

A celebrity bee

This Yellow-banded Bumblebee has continued to visit our back garden. I feel like a paparazzi because I’ve taken so many photos and videos of it.

A profile pic.

Yellow-banded Bumblebees are medium-sized with alternating yellow and black bands. They look particularly round and fuzzy because of their short, even body hair and short heads. In one of my phone videos, I can see the bumblebee’s yellow moustache, indicating that it’s a male. Also, I’ve never seen this bee collecting pollen, as female workers do.

‘Special Concern’

Yellow-banded Bumblebees used to be one of our most common bumblebees, but their numbers have declined drastically since the 1990’s. Here in Southern Ontario, it is still observed, but it has declined to about 10% of its former numbers (York University study). In 2016, Ontario designated the Yellow-banded Bumblebee a species of ‘special concern’ that should be monitored closely. Why has it declined so dramatically? It’s complicated.

Habitat loss

Yellow-banded Bumblebees are habitat generalists. They live wherever the flowers and nest sites are — woodlands, wetlands, meadows, farmlands, and urban areas. Since they aren’t fussy, why is our changing landscape a problem?

Natural habitats have been cut, plowed, bull-dozed, and paved. Unfortunately, the province is now allowing this to continue unfettered by government controls, and without regard for threatened wildlife. The suitable habitat that remains is fragmented.

For bumblebees, that spells trouble because isolated populations become inbred. According to a York University study, Inbreeding and disease are factors in decline of Yellow-banded Bumblebee: “As bees become more inbred, they encounter difficulties maintaining their populations, but as their populations gets smaller, they have difficulties avoiding inbreeding. So that is one risk factor that could accelerate their decline.”

These study findings are supported by research into declining bumblebee species in Britain. Dave Goulson, founder of the British Bumblebee Conservation Trust, shares similar research conclusions in his easy-to-understand books A Sting in the Tale (available at Ottawa Public Library) and A Buzz in the Meadow (at OPL). When I recently re-read these books, I was startled by the similarities.

Parasites and diseases from managed bees

Early in May, on a birding bus trip to Point Pelee Provincial Park, I saw fields full of greenhouses, after greenhouses, after greenhouses… In the town where we stayed, the many surrounding greenhouses cast an eerie, orange glow on the clouds at night that looked like fire.

Many of these greenhouses grow tomatoes so we can have fresh ones in February, and Canadian-made ketchup. Greenhouse-grown tomatoes are pollinated by managed colonies of Common Eastern Bumblebees, and they tend to have more diseases than wild bees. When these managed bees escape and forage outside in the landscape, they spread disease when they visit the same flowers as wild bees. Again according to the York University study, Yellow-banded Bumblebee inbreeding has reduced their genetic diversity and made them particularly susceptible to diseases spread from managed bees.

Canada now has voluntary guidelines for greenhouse operators to reduce the risk of managed bumblebee escape, and thus reduce the spread of disease to wild bee populations (Bumblebee Sector Guide to the National Bee Farm-level Biosecurity Standard). I hope that these recommended procedures are being followed.

Pathogens and parasites also spill over from managed honeybee hives. Ontario has the highest number of registered beekeepers in Canada, and they help farmers pollinate crops. Increasingly, amateurs are taking up backyard beekeeping in a well-intended effort to help bee populations. (Ontario Species at Risk Evaluation Report for Yellow-banded Bumble Bee (Bombus Terricola)) Unfortunately, if honeybee problems aren’t identified and addressed quickly, they will also spread to, and harm, wild bee populations.

Picky eaters

Still, why are Yellow-banded Bumblebee populations affected more than other types of bumblebees? Some other bumblebee species’ numbers are stable, or even increasing. It turns out that flower preferences, and thus food availability, has also contributed Yellow-banded Bumblebees’ decline. They will visit a wide variety of plants for pollen to feed queen bumblebees and bumblebee larvae. However, they are fussier about the flowers they visit for nectar, their fuel.

A bumblebee’s tongue length determines which flowers it can reach into for nectar. Bumblebee species with long tongues are declining more quickly than others. Wait a minute…Yellow-banded Bumblebees have short tongues. In the podcast A Way to Garden, Beecology: how you can help native bumblebees, Robert Gegear explains that all of the species in decline are in the same functional group — they all visit flowers with longer, tubular flowers for nectar. The short-tongued bees, like Yellow-banded Bumblebees and Rusty-patch Bumblebees, have an innate behaviour called nectar robbing; they bite holes in the base of long flowers to reach the nectar. For more on nectar-robbing, read the Sting in the Tale.

I found holes in obedient plant flowers made by the Yellow-banded nectar-robber in our back yard.

Even though Yellow-banded Bumblebees are habitat generalists, much of Southern Ontario’s landscape is now poor quality habitat, devoid of the flowers these bumblebees need to survive.

Now that we know some reasons why Yellow-banded bumblebees have declined, what can we do to help them?

Plant the right flowers

The easiest thing we can do is plant lots of flowers for them. Since they don’t mind living in urban areas, we can provide new, quality habitat for them in our gardens. We need to include a variety of native plants, eliminate invasive plants and pesticides, and maintain our yards in pollinator-friendly ways.

Beecology is an American citizen science project similar to Bumble Bee Watch. Its website provides specific nectar plant recommendations for declining bumblebee species — the long-tongued bees, and short-tongued nectar robbers that also visit longer flowers. I will be using these recommendations to guide my next plant and seed choices.

This helpful info-graphic, from Beecology, shows the nectar plants needed by declining bumblebee species. Notice that obedient plant is one of the suggested flowers — the same plant where I found nectar-robbing holes in my garden.

Beecology also provides excellent suggestions for pollen-rich flowers used by all kinds of bees. Earlier in the summer, for several weeks, I had no bumblebees in my garden. One reason for their absence was that my garden was missing critical pollen sources. St. John’s wort, meadowsweet, and roses were blooming elsewhere and were covered in bees.

Support conservation organizations

What else can we do? To help maintain and restore habitats on a larger scale, for bumblebees and other wildlife, support conservation organizations. They are at the forefront of research and education, and they are pressuring governments on behalf of wildlife.

You can also help with citizen scientist projects. Bumble Bee Watch, a Wildlife Preservation Canada website, encourages you to submit bumblebee sightings. The data is used to help monitor bumblebee species range and populations, to better understand plant-pollinator interactions, and for other important research. Friends of the Earth also holds the Great Canadian Bumble Bee Count to gather data over a two-month period each summer. Now that I recognize the importance of these projects, I plan to contribute to them.

Hold governments accountable

It will take more than individuals and their urban gardens to restore bumblebee populations, and to protect other wildlife. Everyone needs to do their part, including governments, developers, farmers, and greenhouse operators. Sadly, Ontario’s current government is more interested in financial gain than conservation. Are developers considering wildlife and wilderness during construction? Are greenhouse operators following optional ‘biosecurity’ guidelines? Are farmers reducing harmful pesticides that kill insects and the birds that eat them. We must hold them all accountable. I now sign petitions, buy more organic produce, donate to conservation organizations, and I will vote accordingly.

All alone

It is now August 21st. When I last saw our Yellow-banded Bumblebee, he was tucked under a Joe Pye weed flower — his favourite spot to spend the night. This morning, I’ll check on him to see if he’s still around. I know that adult bumblebees don’t live very long, so I cherish every sighting.

Rock-a-bye beeby, in the Joe-Pye…

For me, he will live on as a symbol. A symbol of the beauty and fragility of nature, and of what we risk losing if we don’t get our act together and take care of the environment. But he’s also a symbol of hope. There is obviously a thriving Yellow-banded Bumblebee nest somewhere nearby that grew large enough to produce queens and males. That’s a good sign. If I can provide habitat for a lone bumblebee, together we can create habitat for many more.

We’re baaaack!: bumblebees return to the garden

In mid-July, all of a sudden, bumblebees reappeared in my garden again. Hurray!

Males and workers

Numbers continue to increase as we now have males and workers in the mix. In late July, nesting queens switch from laying eggs that will become workers, to laying eggs that will become males and queens. Depending on the bumblebee species, workers live from 2 to 6 weeks (according to Buzzaboutbees.net), so there’s an overlap of ageing, foraging workers and new males. So far, I have only seen one young, mammoth queen.

How can you tell whether a bee is a male or a worker? When I find bumblebees sleeping in, or under, flowers and leaves, I know they’re males. Males don’t live in bumblebee nests; they spend their days drinking nectar and looking to mate, and their nights camping out in the garden. They go to sleep very early, as early as 6:00 pm. They also seem prone to napping, and will stick up a middle leg (not finger) to tell others to buzz off.

A male bumblebee sleeping under a Joe Pye weed flower. This lazy-bones was still sleeping at 8:00 am. I’ll give him a break though because he may have been too cool to be active.

Of course, to the trained eye, there are more scientific ways to tell if a bumblebee is a male or a worker: females have pollen baskets (shiny segments with long hairs) on their back legs; males have longer antennae (13 segments, while females have only 12); males have 7 bands across their abdomen instead of just 6; and males have no stingers. Visit the Xerces Society Bumblebee identification for more information.

Size isn’t an indicator of whether a bumblebee is male or a worker because bumblebee workers vary dramatically in size. The smallest bumblebee workers live and work in their dark nest for their whole lives tending to their mother and siblings. Some small workers join their larger sisters in foraging duties outside the nest. Perhaps their differing tongue lengths and body sizes allow them to visit a greater diversity of flowers. A Sting in the Tale, by Dave Goulson of the British Bumblebee Conservation Trust, has been my favourite book for learning about the bumblebees and their life cycle (at Ottawa Public Library).

Common Eastern bumblebees

I used to think that all the bumblebees in our yard were Common Eastern bumblebees. Now that I am learning to identify them, I am noticing look-a-likes, and some distinctly different bumblebees as well. Wildlife Preservation Canada and the Xerces Society provide a handy, single-page PDF ID guide for Bumble Bees of South Central Ontario. The sleeping male above is a Common Eastern bumblebee.

This PDF from Wildlife Preservation Canada and the Xerces Society is a handy ID guide for bumblebees in Southern Ontario.

Brown-belted bumblebees

After reading the Wild Pollinator Partnership blog posts about their pollinator surveys in downtown Ottawa, I decided to take a closer look at the bumblebees in my garden. If a variety of bumblebee species live downtown, they might be in the ‘burbs as well. I discovered that some of my Common Eastern bumblebee visitors are actually Brown-belted bumblebees.

This Brown-belted bumblebee was also asleep, making it much easier to get a clear picture.

Two-spotted bumblebees

Other so-called Common Eastern bumblebees turned out to be Two-spotted bumblebees.

A Two-spotted bumblebee on anise hyssop.
I think this may be a male Two-spotted bumblebee.
I think the male bumblebee above is one of the variations on the bottom, left. This Two-spotted bumblebee guide is from the Bumble Bees of the Eastern United States PDF.

Red-belted bumblebees

I see many Red-belted bumblebees in the front pollinator garden. They love the mountain mint patch, perhaps because their can easily reach its nectar with their short tongues. These workers and males vary in appearance and can easily be mistaken for other kinds of bumblebees.

A standard Red-belted bumblebee worker.
Red-belted bumblebee ID guide from the Bumble Bees of the Eastern United States PDF.
A very blonde Red-belted bumblebee male. I think this pattern variation matches the third or fourth from the left on the bottom row.

Identification resources

I find it very difficult to identify bumblebees, or any insect for that matter, without a picture for reference. I then use the following resources:

A lone, rare bumblebee

We’ve also been seeing an extra-special bumblebee visitor — a member of a rare and declining bumblebee species. More on this lone bumblebee in my next blog post…

The Case of the Missing Bumblebees

Bumblebees are my favourite kind of bee. They’re big, gentle, furry constant companions in the garden – or should be. In late June and early July, I had no bumblebees in my gardens at all. The yard was a lonely place without them. After a lot of fretting, I decided to investigate why there were no bumblebees, so I could do something about it.

Suspect 1: Wool Carder bee thugs

I first blamed male European Wool Carder bees for chasing all the bumblebees away. I really do dislike them and their bullying behaviour. Male Wool Carder bees choose an area with abundant flowers and patrol it, so females they mate with will have a secure supply of food. This year I had multiple males claiming territory in my front and back gardens. They rammed and chased each other, as well as other bees. Here’s a Youtube video, Wool carder bee – defending territory, that shows a male bee driving away another bee. They are easy to spot because they have a distinctive hovering flight, and a stocky, hairless, striped body.

Wool Carder bee males really like penstemons, like this hairy beardtongue.

The local Wild Pollinator Partners has an informative blog post about Wool carder bees. Although there are alarmist stories on the Internet about Wool Carder bees, it turns out that I don’t really need to worry about them. I may not like Wool Carder bees, but they are not guilty of driving all the bumblebees from my garden.

Suspect 2: Bumblebee-mimic robber fly

One day I noticed a large bumblebee, maybe a queen, carrying another bumblebee. In the book A Sting in the Tale (at the Ottawa Public Library), by Dave Goulson, I had read about internal bumblebee nest conflicts, but never about a queen carrying a worker away. So strange.

A bumblebee-mimic robber fly eating a Common Eastern bumblebee worker.

It turns out that the larger ‘bee’ is actually a bumblebee-mimic robber fly with quite an amazing disguise. It is eating the smaller worker bumblebee! Visit the Wild Pollinator Partners blog posts Big-eyed bumblebee and Bumble bee imposter to read about robber flies. The robber fly in my photo is Laphria thoracica. Its large eyes, short antennae, and 2 wings (as opposed to 4) indicate that it is a fly instead of a bee.

Did this robber fly kill all my bumblebees? Probably not. It must have fled the murder scene because I never noticed it again. Also, robber flies eat other kinds of insects too, not just bumblebees. If it stuck around it could have eaten some of the Japanese beetles in my yard.

Suspect 3: Crab spider

I’ve noticed more insect diversity in my garden this year. Many of them predators and parasitoids that feed on other insects. Their presence indicates that I have created a healthy ecosystem in my yard.

One morning, this Goldenrod Crab Spider was in my back garden waiting to ambush a foraging bee when it landed on a Knautia macedonica flower. Crab spiders grab insects with their long front legs, inject them with paralyzing venom, and suck out the contents of their body.

I got tired of watching this spider. Perhaps it also got tired of waiting here. I never saw it again. He was quite poorly camouflaged on the red flower, so maybe the bees noticed it just like I did. Besides, Bicoloured Striped Sweat Bees were visiting these flowers, not bumblebees.

Suspect 4: Mother Nature

Mother Nature delivered a strange mix of weather extremes this spring and summer. Bumblebees had a difficult time with the cold, late spring and a very hot, humid July. Was the weather to blame for the lack of bumblebees?

The cold spring weather caused queen bumblebees to emerge late, and start their nests late. Once a queen bumblebee lays eggs, it takes about a month for them to develop into the first batch of workers. By early June, I saw the first workers. I also still saw queens foraging, which meant that the workers weren’t able to return enough food to the nest, so the queens had to join in to help. Bumblebee colonies are already under severe time constraints to gather resources and grow as quickly as possible, so the late start jeopardized their success.

By the time I started to see more worker bumblebees in the garden, the extremely hot and humid weather hit. According to Bernd Heinrich, in Bumblebee Economics (at Ottawa Public Library), Bumblebees can only forage when their body temperature is between 30°C and 44°C. They have adapted to function in cool temperatures; their furry bodies, and ability to shiver to warm themselves, allows them to forage and heat their nests in cooler temperatures. If it’s too hot, they can’t forage, and they don’t store large surpluses of pollen and nectar to use in the meantime.

Wild fluctuations in temperature, such as our cold spring and very hot early summer, are a consequence of climate change, not Mother Nature’s whims. The normal dips and wobbles in the Polar Jet Stream (Wikipedia) become more persistent and are amplified, causing odd weather extremes, according to the Discover Magazine article What’s up with all this wild, weird weather. For information on studies of how climate change is threatening bumblebees, visit Bumble bees being crushed by climate change, Climate change is killing off bumblebees, and Bumblebees affected by 2018 extreme UK weather. Sadly, bumblebees seem to be the climate-change canaries in the garden.

Missing flowers?

Were the bumblebees out there visiting other gardens, instead of mine? The strange weather caused some plants to bloom late. My anise hyssop plants, which have been a bumblebee favourite for the past two years, bloomed weeks later than before and I lost several of my largest plants. When it finally did start to bloom, there were no bumblebees around.

Bumblebees on anise hyssop last summer (2018).

I searched around the neighbourhood to see if bumblebees were in other gardens with different plants. I did find a few on non-native rugosa roses and false spirea. I asked other gardeners if there were bumblebees in their gardens and what plants they were visiting. Based on their replies, it seems that bumblebee numbers were down elsewhere too. Others were seeing bumblebees on the following native plants: spiderwort, spirea shrubs such as meadowsweet and steeplebush, and St. John’s wort. I’ll be adding these to my garden to ensure that I have back-ups and a consistent succession of blooms.

This mystery turned out to be more complicated than I expected, and there’s no specific villain to blame. In the end, since mid-July, there have been so many bumblebees visiting my garden — I am so relieved! While they had a late start, they are now abundant. I appreciate their company more than ever.

The Fab Four: beetles in the garden

Each year, I notice more diversity in the insects visiting our garden. In particular, this year I am seeing different kinds of beetles, spiders, and moths. Here are four beautiful beetles that I’ve spotted in the garden so far this summer.

Red Milkweed Beetle

Red Milkweed Beetle

Years ago, I saw a Red Milkweed Beetle, but then I never saw one again — until this year. In its various life stages, the Red Milkweed Beetle eats different parts of common milkweed plants — larvae eat the roots, and adults eat leaves, buds, and flowers. Since common milkweed is such a vigorous and spreading plant, the beetles don’t end up causing serious damage. I did notice that this milkweed patch seemed smaller this year, maybe because of this beetle or because of the cold, wet spring.

It is amazing how milkweed supports so many specialized insects, including Monarch caterpillars. For a description of the community of insects living off this plant, read Common Milkweed Insects from the University of Wisconsin-Madison Master Gardener Program.

Six-spotted Tiger Beetle

A beautiful Six-Spotted Tiger Beetle.

This lovely, metallic beetle surprised me as I was pulling weeds. It jumped onto a piece of cardboard destined to smother a patch of creeping bellflower. This beetle actually made a scraping sound as it jumped around the cardboard, which made me stop and take notice.

The Six-spotted Tiger Beetle is a voracious predator of spiders, ants, caterpillars, and other arthropods. It is one of the beneficial insects that help prevent other insect populations from getting out of control. The Nature Web has an interesting article about them, A Dazzling Green Beetle: Six-spotted Tiger Beetle, as does The Bug of the Week blog post Tiger, Tiger Burning Bright.

Orange-spotted Lady Beetle

Well, this ladybug has it’s colours backwards! I have seen orange ladybugs with black spots, but never a black ladybug with orange spots. It turns out that this lady beetle isn’t mixed up, it’s an Orange-spotted Lady Beetle. According to BugGuide’s Info page on this beetle, it is also often associated with milkweed, but I saw it on another plant.

Ladybug’s are another one of my garden helpers, eating aphids and other insects feeding on my plants. I even saw a regular red and black ladybug, and a cluster of its orange eggs, on the American highbush cranberry in June. The shrubs were covered in Viburnum Leaf Beetles, so there were a lot of destructive, little larvae for them to eat.

Firefly

Well fireflies have been the stars of the summer garden, pun intended. Each evening between 9:00 pm and 9:30 pm, for the past few weeks, the whole family has been sitting outside to watch their show! I only discovered fireflies in the garden a couple of years ago, but I have never seen so many before this July.

Most often, fireflies flash to communicate while they’re looking for a mate. The fireflies we’ve seen flash in different colours of yellow, green, and red all over the yard, even up in the trees.

I noticed this unfamiliar beetle systematically walking around an anise hyssop plant. It is actually a type of firefly, a Winter Dark Firefly. Fireflies eat soft-bodied insects, like slugs, snails, worms, and the larvae of other insects. I guess it was hunting for its next meal. I didn’t know that fireflies are active in the daytime, as well as at dusk.

After reading information on firefly.org, I see that the native plant pollinator habitat I’ve been creating in my yard is actually perfect firefly habitat too. Visit their pages on How to Build Firefly Habitat and Plants for Fireflies for details.

The Giant, the Monarch, and the Fairy: my garden fable

As I add native plants to our garden and attract more wildlife, it increasingly feels like a magical place. In the past week, I saw a Giant, a Monarch, and even a fairy. A magical place, indeed! Okay, so I didn’t really see a fairy — it was a hummingbird, which was such a surprise visitor that it might as well have been a mythical fairy. (The only thing my fable is missing is a talking animal; while I do talk to our dog, he doesn’t talk to me.)

The Giant

One day as I worked in the back garden, I looked up and saw a spectacular butterfly — a Giant Swallowtail was flitting from one patch of red valerian to another. What a big, beautiful butterfly! It frantically flapped its wings while it drank nectar, as you can see in my Youtube video. With the constant wing-flapping and moving between plants, it was very difficult to photograph.

A Giant Swallowtail butterfly drinking nectar from non-native red valerian.

Then, the butterfly circled one of the hop trees in our hedgerow ‘fence’. Hop trees and prickly ash are its northern host plants, both of which are in the citrus family. Non-native rue (the herb) and gas plant also serve as host plants. I bought my hop trees from Beaux Arbres Native Plants, and from Fuller Native Plants (sadly, now closed). Since then, I’ve been checking the hop tree for caterpillars, but I haven’t seen any. Their caterpillars are camouflaged to look like bird poop.

Giant Swallowtails have only been seen in Ottawa since around 2012. Experts believe climate change is the main reason these butterflies are now showing up north of New York state and Point Pelee Provincial Park, their previous northern limit. For more information, you can read The giants have arrived: Giant Swallowtails spotted locally (written in 2013), and Giant Swallowtails and Climate Change (from 2011).

The Monarch

While I’ve already seen a couple of Monarch butterflies quickly passing through the garden, they didn’t stop to drink nectar or lay eggs. However, now that the common milkweed in our front yard is in full bloom, we finally had a Monarch stick around for a while. Since that day, July 12th, we’ve seen Monarchs daily.

In this brief video, you can see that the Monarch is much calmer while she sips nectar than the Giant Swallowtail. And yes, I pulled the photo-bombing dog-strangling vine!

Our first lingering Monarch visitor of 2019. (July 12, 2019)

This Monarch, and others, have been laying eggs on the common milkweed patch. My son and I have found numerous eggs. We didn’t find any caterpillars. Only a small percentage of butterfly and moth caterpillars make it to adulthood; they are frequently victims of the spiders, wasps and ants.

We decided to collect 3 eggs to increase their chances of survival, and to watch their growth and transformation into butterflies. It does seem like a big commitment raising Monarch caterpillars. I wouldn’t want to take this on at a larger scale. Instead, I will keep planting more milkweed for Monarch caterpillars and nectar plants for adult Monarchs. Mother Nature can do the rest.

The Fairy

On July 15th, I spotted a hummingbird visiting several different flowers in our back garden. What a treat! In this video, you can see the hummingbird at the red bee balm, and a pink cultivar of Culver’s root (that I bought by mistake). Oddly, it really liked the Culver’s root because it visited twice. The flowers are probably chock-full of nectar because I have no bumblebees. I hope this early hummingbird visitor sticks around.

I have been trying to tempt hummingbirds to our yard for years. For most of that time, I just had a sugar syrup feeder. What a pain they are to keep clean! If the syrup spoils, it is very dangerous for hummingbirds. Every year, once the weather gets too hot, I end up just taking the feeder down.

A few years ago, I finally got serious about attracting hummingbirds. I planted red and orange tubular flowers, both native plants and annuals. The native plants I grow for them, and that hummingbirds visit, are red bee balm, royal catchfly, cardinal flower, fireweed (purple), and jewelweed. I also grow some early flowering native plants to help hummingbirds during spring migration: Canada columbine, limber honeysuckle, fly honeysuckle, and clove currant. We have also seen them visiting annual cardinal climber, petunia excerta, and Mexican torch sunflower.

I have also added plants that will attract small insects. I already knew that hummingbirds eat their weight in a day, but I was surprised to learn that as much as 80% of their diet consists of insects and spiders. Baby hummingbirds eat only insects and spiders. I frequently see New Jersey tea recommended to attract small insects, so I bought a few this spring from Ontario Native Plants. A lot of native perennials that I already have in my garden, such as goldenrods and asters, attract small insects too. For more information, see How to Feed a Hummingbird, Part 1: Insects and Protein, and How to create a hummingbird-friendly yard.

The moral of this story

Fables always teach a lesson. So, what is the moral of my fable? “Don’t go inside because you might miss something interesting in the garden?” That doesn’t sound right, even though I do feel this way sometimes. “Plant it and they will come.” Yes, I think that’s it — predictable, but true.

Busy leafcutter bees

A few weeks ago, I noticed the tell-tale sign that leafcutter bees are at work in the garden — tidy oval and circular holes in leaves.

Leafcutter bees have been busy cutting pieces from fireweed and lilac leaves in our back garden. (July 2019)

These solitary bees create cavity nests by shaping oval pieces of leaves into tunnels. The finished nests look a lot like green cigars. Smaller circular pieces are used to divide the nest into cells (rooms) for each larvae, or to cap the end of the nest. This Wild Pollinator Partners blog post about Leafcutter bees includes a picture of nests found under a rock.

In our garden, they really like to use leaves from fireweed and rosa glauca. In Bees: An Identification and Native Plant Forage Guide (at Ottawa Public Library), Heather Holm lists other common plants that leafcutter bees use for nesting materials: tick trefoil, St. John’s wort, ash trees, and redbud trees. Over the past couple of years, I found that leafcutter bees used a wide variety of leaves around the yard.

Leafcutter bee holes in basswood (top), rose, maple, and grey dogwood (bottom) leaves from 2017 and 2018.

Within each brood cell, a female leafcutter bee makes a ball of pollen, called bee bread. She then lays an egg on top of the bee bread, and closes up the brood cell. When the bee larvae hatches from its egg, it eats the bee bread as it grows. The larvae then forms a cocoon where it develops into a bee.

I’ve managed to catch a few leafcutter bees cutting pieces from the fireweed leaves (Youtube video). They are amazingly quick at cutting each leaf piece. Sometimes they stop cutting part way and abandon it, perhaps because the leaf is too tough. Once they finish cutting a leaf piece, they struggle to carry the extra weight. I often see them stopping to rest, with the leaf piece still in their mandibles, on their way back to the nest.

Despite comparing my photos of leafcutter bees with those in identification guides and web sites, I am not sure what kind of leafcutter bees are living in our yard. My bee identification skills have a long way to go.

Nest sites

Both this year and last, leafcutter bees have been making nests between rocks in the dry-stone walls of our terraced garden. Here’s a video of a leafcutter bee returning to its nest, and then leaving again. Since the bee isn’t carrying a leaf piece, it is provisioning the nest with a load of pollen, which you can see on her underside. There are at least three bees currently nesting in our rock walls. I’ve read that they like nesting near each other.

A leafcutter bee is making a nest beyond the triangular opening in the second (from the top) row of rocks.

In 2017, we watched leafcutter bees making nests in the frames of our metal lawn chairs. Sometimes they had trouble getting into their nest entrances with the big leaf pieces, so we cheered them on, and were relieved when they finally succeeded. Now, our main seating area is located next to the stone walls where the leafcutters are nesting, so we again have a front-row seat to watch their activity. Such fun to watch!

Leafcutter bees will also use artificial bee boxes. If you do choose to place a bee box in your garden, make sure to line the tubes with paper that can be replaced every 1 or 2 years. This simple stem will help reduce the spread of parasites and fungal diseases between adjacent nest sites. For more information on bee box maintenance, see The horrors of mass-produced bee houses.

Foraging

Leafcutter bees are relatively easy to spot on flowers because they tip the end of their abdomen up in the air. They also carry pollen on hairs underneath their abdomen, instead of on their back legs.

This leafcutter bee is collecting pink pollen from red scabiosa flowers. (July 2019) You can differentiate leafcutter bees from other foraging bees because they tip their back end up. They also carry pollen underneath their abdomen, which makes their underside bright yellow, or in this case bright pink.

I usually find them on flat, open flowers with a daisy-type shape. According to Holm, leafcutter bees are generalist foragers and will gather nectar and pollen from a wide variety of flowers.

A mysterious, lurking bee

As I watched the leafcutter bees coming and going from their nests, I spotted a smaller bee hanging out nearby. At first, I thought it might be a male looking to mate.

Then, I noticed that the bee had a very pointed abdomen. Uh-oh, I recognize that shape from pictures of parasitoid cuckoo bees. I didn’t have my phone, so I have no photo of the bee, but I believe it was a Modest Cuckoo Leafcutter Bee (see BugGuide). As usual, wherever there are bees, there are other insects that prey upon them, one way or the other.

I parked myself near a nest, with a cup of coffee, waited and watched. Sure enough, once the leafcutter bee flew away, the cuckoo bee entered the nest to lay its eggs. The pointed tip of the cuckoo bee’s abdomen is used to pierce the pollen ball to insert, and hide, its own eggs. When the cuckoo bee eggs hatch, they will eat the leafcutter larvae and the pollen that was left for them. For more on cuckoo bees, see the Restoring the Landscape page Native Bee Spotlight: Cuckoo Bees – Coelioxys spp. I’m wish this didn’t happen to ‘my’ leafcutter bees, but I know it is just how nature works.

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.