Holes in Leaves? You Might Have Leaf Cutter Bees.

Leaf cutter bees (Megachilidae family) are solitary bees, meaning they don’t live in hives like honeybees and aren’t aggressive. Unlike honeybees, they carry pollen on the underside of their abdomen, called the scopa, rather than on their legs. They are master architects, using leaf pieces to construct individual nests for their young.

These bees are excellent pollinators, often more efficient than honeybees for certain plants! They visit a wide variety of flowers, transferring pollen as they forage for nectar and pollen to feed their larvae. By supporting leaf cutter bee populations, you’re boosting the biodiversity and health of your garden. They’re particularly important for pollinating crops like alfalfa, but also contribute to the success of countless other flowering plants.

Spotting a Leaf Cutter Bee

Leaf cutter bees are generally small to medium-sized, ranging from ¼ to ¾ inch long. Their appearance varies depending on the species, but they are often dark in color (black or brown) with pale hairs on their abdomen. The key identifier is their pollen-carrying mechanism: look for pollen on the underside of their abdomen, not their legs like you would see on a honeybee. However, actually seeing these bees is less common than seeing the results of their work on your plants. 

Tell-Tale Signs of Leaf Cutter Bees: Circle Holes in Leaves

The most obvious sign of leaf cutter bees is the neat, semi-circular or circular cuts they make in foliage. These bees aren’t eating the leaves; they’re collecting material to build nests for their larvae. These cuts are typically found on the edges and look like perfect round holes in leaves. The holes do not significantly harm the plant’s overall health. Roses are common targets, but they’ll also use leaves from other plants like ash, lilac, and even some vegetables.

Damage vs. Disease: Leaf cutter bee damage is very distinct and easy to identify. It’s important to distinguish it from plant diseases or damage caused by other pests. Unlike disease, there’s no discoloration; you’ll just see clean cuts. Remember, these are not pests; they’re simply borrowing a bit of foliage.

Why the Circle Shapes in Foliage? The precise, consistent shapes are crucial for nest construction. These bees meticulously cut and shape the leaf pieces to create individual cells within their nests, each designed to house a single larva. The circular or semi-circular shape likely provides the best structural integrity for these cells.

Where You’ll find Leaf Cutter Bees

Leaf cutter bees are widespread and can be found in a variety of habitats, including gardens, meadows, and woodlands. They are most active during the warmer months when flowers are abundant. Look for them visiting flowering plants, especially roses, alfalfa, and clover. Providing nesting habitats, such as drilled wood blocks or bee houses, can encourage them to take up residence in your garden.

These friendly neighborhood pollinators pose almost no threat to humans or property. In fact, their presence indicates a healthy and diverse ecosystem. Embrace the unique leaf patterns as a sign that your garden is a haven for beneficial insects! Resist the urge to treat them as pests; instead, welcome them as valuable partners in creating a thriving landscape. So, next time you see those perfectly shaped leaf cutouts, think of them as little smiles in your plants’ foliage and take a moment to appreciate another wonder of nature. 

~The Happy Gardener, Lisa Mulroy