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.
Honey Bee Suite