Resident spring bees and visiting butterflies

Since warmer weather arrived here in Ottawa at the end of May, there’s been a lot more pollinator activity in my garden. I’ve observed ground and cavity nesting bees, queen bumblebees, and a few butterflies.

Inconvenient (for me) ground nests

I’ve spotted lots of bees going into ground nests all over the front and back gardens. The entrances can go unnoticed, unless you see a bee going in. More often than not, they’re located right next to plants or under dry leaves. There is a clear preference for sloped areas that are south- or west-facing.

Usually I see a bee arrive, and disappear into an invisible hole in the ground, just as I reach to dig up a plant, clear leaves, or pull weeds. Now, I don’t want to work in those areas to avoid damaging nests, or destroying entrances. I have mistakenly done in the past. It’s sad to watch a bee laden with pollen searching for a nest entrance that’s gone, or that it can’t find because I removed the weeds or leaves it used as landmarks.

Oh well, I guess will just have to skip those chores. A messy garden is better for pollinators, anyway. Now I have more time for bee-watching.

A pair of ground-nests that look like ant hills. I watched a bee go into one of them. Once I started looking, I noticed 4 similar hill. Most other nests I find are well-disguised instead of in an open space.

Lurking parasitoids

This spring, I noticed two different kinds of insects hovering and zig-zagging close to the ground looking for nests to prey upon. One of them was the odd bee-fly that is furry like a bee, and has a long ‘beak’ for drinking nectar. Females fling their eggs near ground nest entrances. The eggs will then stick to bees as they enter their nests. When the eggs hatch, the bee-fly larvae consume the bee larvae.

Notice the fur and ‘beak’ on this bee fly. It was close to the easy-to-spot ground-nests pictured above.

I also think I’ve seen a few kleptoparasitic cuckoo bees that have distinctive hairless, red abdomens. (I’m using a picture of a nomadic cuckoo bee on Heather Holm’s Instagram page to tentatively identify the bee, from memory.) Cuckoo bees enter ground nests of other bees to lay their eggs. Once the eggs hatch, the larvae eat pollen left for the original ground-nests’ residents.

It seems like bees abandon nests if they spot parasitoids/kleptoparasitoids nearby. I stopped seeing bee activity in several locations after I had spotted the cuckoo bee flying in the vicinity.

Cavity nests

The only cavity-nests I’ve found so far are for small carpenter bees. In the backyard, they’ve been digging nests in last year’s ironweed stems.

Small sweat bees excavated nests in ironweed stems. (The flowers and leaves belong to a self-seeded columbine cultivar.)
In this close-up you can see the small carpenter bee’s back end just inside the stem. Queens block the entrances to protect the enclosed eggs and larvae.

I think I’ve seen mason bees on crabapple flowers and Virginia waterleaf flowers. I wonder where they’re nesting? Perhaps they’re using the cup plant stems I left for them; I cut the stems off about 15 inches from the ground, and added the top part of the stems to a brush pile.

What I believe is a mason bee on a ‘Prairie Fire’ crabapple blossom. This bee was larger and stockier than others, with a shiny, hairless body.

Bumblebee nest

I’m pleased that a queen bumblebee has chosen to make a nest in our yard. A first for us! It is under our shed in a former groundhog den that was later used as a mouse nest. Unfortunately, it is too close to the shed door for my liking, so the area is now fenced off.

I think a bumblebee queen is nesting under the shed in an former groundhog den/mouse nest. Several times, I’ve seen a queen leaving or entering the opening to the left of the big dandelion.

We’ve watched numerous bumblebee queens searching around the backyard, especially the perimeter, for nest sites. Almost all of them check out the chipmunk den entrances in our terraced garden. They hover close to the ground, flying back and forth, going under leaves and under rocks, and then coming out again. Here’s a Youtube video I found, called Bumblebee Queen in Search of Potential Nest Locations, that shows the searching flight pattern bumblebee queens use to find nest sites.

Butterfly visitors

We’ve had a few butterflies visiting the garden, usually American Ladies and Red Admirals. (BugGuide has a handy picture for distinguishing American Lady and Painted Lady butterflies.) Other types passed through too quickly for me to photograph or positively identify.

This American Lady hung out in the sun near one of her host plants, field pussytoes.
After tasting several globe thistle plants, this tattered American Lady finally laid eggs on our patches of pearly everlasting. She’s curving her body to deposit an egg.
Red Admiral butterfly basking in the sun.

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