Navigate / search

Planting a garden for leafcutting bees

Whenever I write about leafcutters, someone from the Entomological Society of America writes to remind me that the official common name is “leafcutting” bees. To me, the phrase “official common name” is an oxymoron. The official name is the Latin scientific name, and the common name is what the local people call it.

I understand that entomologists want to reduce confusion, but isn’t that what the Latin name is for? I simply love to hear local variations in names. Furthermore, I think that insisting on a “official” common name destroys a rich treasure trove of vocabulary.

My favorite example is a gem. The group of insect pollinators that we northerners call “hover flies” are often referred to in the southeastern states as “steady bees.” Now granted, a hover fly is not a bee, but once you see one of these creatures defy gravity, you know exactly what either group is referring to, right?

Leafcutters are fun to watch

As winter approaches I like to think about my pollinator garden. This year I’m fixated on leafcutters. As far as wild and native bees go, I think the leafcutters are one of the most charming groups. The way they hold up their pollen-coated abdomens is absolutely endearing. Their arched backs always remind me of gymnasts and dancers.

Two summers ago, in 2015, I had a succession of leafcutter species all season long, one right after the other. This past year, I had some but not nearly as many. So I’ve been doing some research to find out exactly what to plant for them.

Leafcutting bees are closely related to the so-called mason bees. They are both in the family Megachilidae (which means “large jaws”). Most of these species live in cavities, so it is easy to get them to nest in tubes, reeds, and straws.

Most of the leafcutting bees are in the genus Megachile (meg-uh-KYLE-ee). They collect and store pollen much like other natives, but they cut circles out of leaves and petals to use for nesting materials. If you are quick, you can sometimes see them carve the discs and fly away with them. Or you can see them arrive at their nest and force the piece into the nesting tube. The pieces are used to line the nest, build partitions, and close off the entrance.

Alfalfa leafcutters are small and quick

Most often we hear about the alfalfa leafcutting bee (Megachile rotundata), an introduced species. They’ve escaped from the alfalfa (lucerne) fields they were imported to pollinate, and now they occupy a wide range of habitats. These small bees are quick and not nearly as spectacular in appearance as some of the native species, but they are still fun to watch.

I will never forget standing in an alfalfa leafcutter domicile in eastern Washington, inhaling the fragrance of fresh-cut alfalfa wafting from the nests. The leafcutters zoomed to and from the domicile with the frenzied gentleness of a honey bee swarm, completely ignoring me.

Most of the leafcutters I have here at my place are larger than the alfalfa leafcutters, more similar in size to a honey bee. But leafcutting bees have a different physical presence. As I mentioned before, they hold their abdomens aloft, giving them an arched appearance. And they often hold their wings out to the side as they forage. Their abdomens are large, rounded on the bottom, and often laden with pollen.

Attract leafcutters with the things they need

To attract leafcutters to your garden, you need to provide the things most bees require: sources of pollen, nectar, water, nesting sites, and building materials. Having watched leafcutters for a number of yeas, I’ve noticed that the flowers they forage on are not necessarily the same ones they use for building. I want to provide both, if I can figure out what those are.

Last year, my leafcutters loved cosmos for both building and foraging. They adored the blue bells (Campanula) for foraging, but I never saw them build with it. They used the leaves of my Clematis but never touched the flowers. This year, they frequently foraged on the open-centered dahlias, sunflowers, mints, and phacelia but never harvested any discs from those flowers. Many leafcutters love to build with the petals of Clarkia (farewell-to-spring) and some species use Clarkia exclusively.

Of course, many leafcutters get sprayed for stealing bits of rose and lilac leaves. This is sad, of course, because, although the leaves look like they were hit with a shotgun, the plant is not permanently damaged. I’ve also seen leafcutters use both the flowers and leaves of Thunbergia (black-eyed susan vine) for discs, but I don’t know if they forage there. They also use the petals of partridge pea.

What else should I plant?

So far this fall I’ve order Clarkia and Cosmos for next year. I have the dahlia tubers from this year, and I hope to get some more Campanula. If you know of anything attractive to leafcutters, I would love to hear from you.

Rusty
Honey Bee Suite

Leafcutter-she-bee
This leafcutting bee is foraging on Phacelia. You can see the thick hairs on the underside of her abdomen. This area is used for collecting pollen. © Rusty Burlew.
Leafcutter
This is an alfalfa leafcutting bee. © Rusty Burlew.
Leafcutter-on-dahlia-4
This leafcutter is foraging on a dahlia. You can see her large mandibles (big jaws) and the edges of her hairy abdomen. Also note how she holds her wings out to the side while foraging. © Rusty Burlew.
Cosmos-with-bite-marks-Rusty-Burlew
This honey bee is foraging on a cosmos that was damaged by a leafcutter. © Rusty Burlew.

 

Megachile perihirta, the furry leafcutting bee

The furry leafcutting bee, Megachile perihirta, is one of my favorite pollinators because it is large and showy. From a distance, this bee could easily be mistaken for a honey bee. But up close, it is hard to miss the large abdominal scopa where the leafcutting female carries her pollen load.

About the size of a honey bee, these bees are native to the western parts of North America. They are summer visitors, often seen in July and August. Although they forage on many different plant species, they have a preference for flowers in the Asteraceae family.

Like all leafcutting bees, the female of this species cuts round sections of leaves and petals to line her nest and build divisions between the egg chambers. Although many leafcutting bees nest in hollow reeds and beetle borrows, this species prefers underground tunnels.

I wasn’t able to photograph a male, but the males have distinctive white “mittens” on their forelegs and a white face. Soon after they mate, the males disappear for the year and the females begin to work at provisioning their nests.

The open-centered dahlias that I mentioned in a previous post turned into a playground for these bees. The leafcutters work fast, flit around in the flowers, and pose beautifully. Yesterday, my camera sounded like it belonged to a fashion photographer. As the bees strutted around on their flowery runway, and I just kept snapping away, trying to capture the perfect expression.

Rusty
Honey Bee Suite

Leafcutter-on-dahlia-1
The furry leafcutting bees have taken a fancy to the open-centered dahlias. © Rusty Burlew.
Leafcutter-on-dahlia-2
Leafcutting bees have a characteristic posture, holding their abdomens high. © Rusty Burlew.
Leafcutter-on-dahlia-3
A view from the rear. Leafcutting bees often hold their wings out to the side when they forage, something honey bees seldom do. © Rusty Burlew.
Leafcutter-on-dahlia-4
Leafcutting bees have large mandibles, perfect for cutting leaves. In fact, the name Megachile means “large jaws.” © Rusty Burlew.
Leafcutter-on-dahlia-5
Here you can see her tongue. Although these bees are polylectic and will forage on many different plants, they seems to favor those in the Asteraceae family. © Rusty Burlew.
Honey bee and M perihirta
You can see that the honey bee (left) and furry leafcutting bee are about the same size. © Rusty Burlew.

Perfect disks or ragged holes?

Point of view is everything. On Monday evening I attended a pollinator meeting in Olympia. Part of the discussion centered on leafcutting bees and how gardeners often lament the damage the bees inflict on their precious plants, as in “Oh no! Look what they did to my roses!” On the flip side, bee lovers are ecstatic, “Oh my! Perfect circles!”

If you’re not sure of my position in this debate, here are some photos of exquisitely missing disks. The leafcutting bees use the leaf and petal pieces to line their nests and build partitions. You can tell the size of the bee by the diameter of the circle. I have several species living here, Megachile rotundata, the small alfalfa leafcutting bee, the larger western leafcutting bee, Megachile perihirta, and another even bigger one that I haven’t yet identified.

I can’t tell you how many hours I’ve spent trying to photograph a leafcutter cutting, but I have never seen it happen. I sometimes see them dragging disks into their tubes, but so far, no cutting. If I leave the garden for even an instant, more circles appear. Perhaps I need a duck blind or a suit of camo.

Rusty
Honey Bee Suite

Leafcutting-bee-Rusty-Burlew
Leafcutting bees are easy to identify by the way they hold their abdomens. This one has a load of yellow pollen. © Rusty Burlew.
Cosmos-with-bite-marks-Rusty-Burlew
This honey bee isn’t bothered by the cut petals. It appears that the leafcutting bee was interrupted and left her prize dangling. © Rusty Burlew.
Purple-cosmos Rusty Burlew
This bumble bee is equally unperturbed by the leafcutter damage. © Rusty Burlew.
Cosmos-with-holes-Rusty-Burlew
These perfectly round cuts look they were done by machine. © Rusty Burlew.
Partridge-pea-Rusty-Burlew
Here the cut-outs were taken from a partridge pea. © Rusty Burlew.
Purple-cosmos Rusty Burlew
The leafcutting bees get both pollen and nesting materials from cosmos. © Rusty Burlew.
White-cosmos-Rusty-Burlew
White cosmos are equally popular with the leafcutting bees. © Rusty Burlew.
calloped-cosmos-Rusty-Burlew
This scalloped cosmos is fast disappearing. The little spider probably thinks it’s a good hunting ground. © Rusty Burlew.

Cosmos: a multipurpose bee flower

I planted two different types of pollinator seed mixes this year, not for the bees to tear up, but to provide pollen and nectar. Both the mixes contained cosmos varieties that grew tall and strong.

At first, I noticed only bumble bees and honey bees nectaring on the blooms, but almost immediately I saw big arcs cut out of the petals. “Who’s that?” I thought, ready to blame some other type of creature. But then I began seeing leafcutting bees—at least three different species—all over the flowers. They are shy, so you have to sneak up on them and pretend you don’t have a camera.

It just so happens that capturing a leafcutting bee cutting a leaf was one of my photographic goals for the year. But in spite of the ragged flowers, I cannot find one bee in the act. Lots of males drink the nectar, and lots of females collect the pollen, but so far they won’t carve a petal in front of me.

So if you’re taking notes on these things, you can try planting cosmos as a leafcutting bee attractant. I’m putting it on my list for next year. Till now, I never thought of cosmos as anything but a nectar and pollen plant, but who knew?

Rusty
HoneyBeeSuite

Cosmos-after-leafcutters
This cosmos bloom now has scalloped edges, thanks to the leafcutting bees. © Rusty Burlew.
Leafcutter-he-bee
This is a he bee and not the one doing the damage. Note the fringed forelegs and white face—both are common on male leafcutting bees. © Rusty Burlew.
Leafcutter-she-bee
This is a she bee (on physalia) as evidenced by the hairy scopa on her abdomen. Leafcutting bees often hold their wings out to the side instead of folded over their backs. They also hold their abdomens high, probably to keep the pollen from rubbing off. © Rusty Burlew.

Leafcutting bees in action

Leafcutting bees are everywhere. Dozens of them nest in my backyard, and I’ve seen alfalfa fields served by massive leafcutting domiciles containing millions of these little bees. I’ve photographed them drinking nectar, collecting pollen, carrying leaves, and building nests, but I have never—ever—seen one cutting leaves.

But a few days ago, I happened across this YouTube video of a leafcutting bee doing what she’s known for. The video is about four minutes long, but the first minute is the best.

I was amazed at how fast these little bees cut out what they need. The circles have smooth and clean edges, but it’s the speed that fascinates me. The other odd thing is that they sit on the piece they’re cutting out. You would think they would drop to the ground as the disk breaks loose, but no. They have everything well under control.

The photo beneath the video is one I took at home. The leafcutting bees here prefer to nest in the hollow spots between the mason bee tubes, even though tubes of the proper size and shape await just a few inches away. They usually use leaves to line their nest, but some prefer petals.

After watching the video, I’m tempted to plant a Thunbergia (black-eyed susan vine) just to see if the leafcutters will slice away. I’m not sure how picky they are about the things they use. In the alfalfa fields, even though I don’t see them cutting, the domiciles smell thickly of alfalfa, an odor that reminds me of barns and silage and horses . . . heavenly.

I hear leafcutting bees love roses, but I’m not into roses because of all the deer we have here. So tell me, what do leafcutting bees cut in your area. Any suggestions?

Rusty
HoneyBeeSuite

Leafcutter-with-petal
The leafcutting bees at my place like the empty spaces between mason bee tubes for their nests. This bee has a piece of yellow petal, but I don’t know what it came from. © Rusty Burlew.
Leafcutting-domicile-2
A domicile like this contains tens of thousands of leafcutting bee holes. The domiciles are placed at regular intervals throughout the fields. © Rusty Burlew.