Have you noticed any circles missing from the edges of your rose leaves? Do some leaves look like little violins?
If you answer yes to those questions, congratulations! Leafcutter bees have taken a fancy to your garden.
Leafcutter bees are native bees and important pollinators for our native plants. These bees are a bit larger than a honeybee and are dark gray with hairy white bands.
Female leafcutter bees cut circular snippets from rose leaves to create wrappers to line brood cells for their young. Think of these rose snippets as blankets for baby bees.
It can take as little as 10 seconds for a leafcutter bee to use her mandibles (jaws) to cut a snippet and fly off to her nesting site. Check for yourself on my short film called The Leafcutter Bee I posted to YouTube.
After seeing the speed at which she can land, snip and fly away it’s no wonder leafcutter bees are included under the family Megachilidae which means “big-lipped.”
It’s not easy to catch these bees in action because they’re so speedy. However, earlier this season I staked out a spot near their favorite climbing rose and patiently waited with camera in hand. Finally one bee flew in and tried landing on a leaf or two before finding the perfect one.
After cutting the leaf, she flew off to her nesting site. The site could be in holes found in a piece of old wood, stems of plants with pithy centers or anything with a hollow center. One year I found leaf snippets stuffed in a piece of unused garden hose.
These pieces of leaves are the construction materials for brood cells that are packed with pollen to feed the young. In CSU Extension Fact Sheet 5.576 on Leafcutter Bees, Dr. Whitney Cranshaw explains that leafcutter bees are solitary bees and don’t produce colonies like honeybees.
Instead, leafcutter bees construct “nest tunnels that may contain a dozen or more cells forming a tube 4 to 8 inches long. The young bees develop and will remain in the cells, emerging next season.”
Every summer I watch for evidence that leafcutter bees have been busy in my garden. As soon as I see rose leaves that start to look like Swiss cheese, I know leafcutter bees are happily at work.
Text and images by Jodi Torpey
Denver Master Gardener since 2005