Featured Creature: Leafcutter Bee

What creature carves out little pieces of tree leaves to build its nest inside hollow stems?

The Leafcutter Bee!

Known scientifically as Megachile (genus), leafcutter bees account for 1,500 of the world’s 20,000 bee species. I first noticed the work of leafcutter bees in my own backyard two years ago. First, you notice the “leaf damage” of the leafcutter bee. 

Here is the “leaf damage” on a pin oak seedling. 

The leaf damage takes the form of neat little curves. I recognized these neat little curves from having perused Bees: An Identification and Native Plant Foraging Guide, by Heather Holm, an author whose work I highly recommend. 

In June of this year, I was fortunate enough to capture a leafcutter bee on video doing her work. I’ll show you the video below, but first … 

How can we coexist with critters who are “harming” our plants?

It is said, “If nothing is eating your garden, then your garden is not part of the ecosystem.” If you want your garden to be part of the ecosystem, then some of it will become food for other critters. Some of my leaves will become food for leafcutter bees. But then the leafcutter bees will pollinate my wildflowers and my vegetables, making it possible for them to bear seed and fruit. I am happy to make this trade-off, plus I want my garden to feed all of the living species, not just us humans.

How do leafcutter bees differ from honeybees?

Honeybees are the most famous bees. And who doesn’t like honey? But honeybees are only one species out of 20,000 worldwide.  

Honeybees are social. So they live cooperatively in hives. But most bees are solitary, including leafcutter bees. They interact only in mating. And then they make their nests and lay their eggs in a nest that could be in the ground, or in a rotting tree or in the hollow stem of a dead wildflower.

The North American continent is home to 150 of the world’s 1,500 species of leafcutter bees. Honeybees originate from Europe; they are not native to North America. 

An “unarmed leafcutting bee” from my backyard

Here is a video of an “unarmed leafcutter bee” in my backyard, cutting the leaf off a pin oak seedling. This female uses her strong mandibles (jaws) to carve out a piece of a pin oak leaf to build her nest. Notice how quickly and efficiently she does this work.

How do I know this is a female? Because only the females build nests. The males die shortly after mating. 

As soon as she is done cutting off the piece of leaf, she carries it back to the nest. The female nibbles the edges of the leaves so they’ll be pulpy and stick together to provide the structure for the nest.

Where is she building a nest? 

She may build her nest in the hollow stem of a dead wildflower stalk, such as ironweed or goldenrod. She may build her nest in a dead tree. (Forest ecologists say that a dead tree is at least as valuable as a live tree, because so many critters make their nests in them.) Or she may build it in the ground. Nests also include cavities in rocks and abandoned mud dauber nests (Holm, 2017).

Here is the nest of a ground-nesting bee. In this case, it may or may not be a leafcutter bee.

If we leave bare spots on the ground, then this becomes a potential nesting site for ground nesting bees, including some leafcutter bees.

What purposes do the leaves serve?

Leaves prevent desiccation (drying out) of the food supply. The leaves typically include antimicrobial properties, preventing the nest from being infected.

Inside a nest, cells are arranged in a single long column. The female constructs each cell with leaf pieces, placing an egg along with pollen mixed with nectar, enough food for the bee to grow to adulthood, before leaving the nest.

In the fall, the larvae hatches from the egg, eats the nectar and pollen, and gains enough energy to grow through several stages, called instars. But it does not yet leave the nest. In the spring, the larvae pupates and becomes an adult, finally crawling out of the nest.

In the eastern U.S., common nesting materials include rose, ash, redbud and St. John’s wort. See below for photos from my home landscape showing the work of leafcutter bees on my pin oak, silver maple and jewelweed.

Where do leafcutter bees gather pollen and nectar?

Heather Holm, author of Bees: An Identification and Native Plant Foraging Guide, lists the following forage plants where leafcutter bees gather nectar and pollen:

Spring Forage Plants: 

• Golden Alexander (Zizia aurea)
• Purple coneflower (Echinacea purpurea)
• Foxglove beardtongue (Penstemon digitalis)

Summer Forage Plants: 

• Black-eyed Susan (Rudbeckia hirta)
• Common milkweed (Asclepias syriaca)
• Butterfly weed (Asclepias tuberosa)
• Joe Pye weed (Eutrochium purpureum)
• Anise hyssop (Agastache foeniculum)
• Blazingstar (Liatris pycnostachya)
• Blue vervain (Verbena hastata)

Autumn Forage Plants: 

• Goldenrod, species of Solidago, including showy goldenrod (Solidago speciosa)
• Asters, i.e., species of Symphyotricum, including New England aster, (Symphyotricum novae-angliae)

Specialist Leafcutter Bees

Some leafcutter bees specialize on the aster family of plants, known as Asteraceae. So we can support these bees around our home landscape by cultivating any representatives of the Asteraceae family, including goldenrod, sunflowers, ironweed and wingstem.

Check out this video of a female leafcutter bee carving out a leaf piece from a China Rose.

More leafcutting from leafcutter bees in my backyard

Here is evidence that a leafcutter bee was carving off pieces of a silver maple leaf (left). Here, leafcutter bees have been working on a jewelweed plant (right).

The following are photos of flowers from my home landscape, all of which make excellent forage for pollinators, including leafcutter bees.

This is my front yard garden from 2022. 

Grow your garden and grow an ecosystem. Cultivate a diversity of native plants and avoid pesticides.

—Hart

Photos by Hart Hagan, except where noted.

Sources and Further Reading:

• Holm, Heather (2017) Bees: An Identification and Native Plant Foraging Guide. Pollination Press. 
• University of Florida, Institute of Food and Agricultural Sciences. Featured Creatures: Leafcutting Bees. 
• https://entnemdept.ufl.edu/creatures/misc/bees/leafcutting_bees.htm 
• Wikipedia: Megachile (genus of bees). https://en.wikipedia.org/wiki/Megachile