There are about 242 species of leafcutter bees in North America, so they are members of a large bee family. They are related to mason bees, and like them, they emerge in spring, mate, and the males die soon afterwards. Females often die soon after they finish laying eggs and seal off their nest.
They look somewhat like the honeybee, and many are similar in size, with similar coloring of gold with black stripes, but they are generally smaller with bigger heads and a more developed jaw area. Some of these sweet little bees are only about 1/5 inch long.
The leafcutter bee has a strong jaw because this bee has the unique habit of cutting plant leaf sections to take back to their nests. They use the leaf cuttings to build and line their nests. This is also why they are named ‘leafcutters.’
This 2:44-minute video by Something Incredible introduces leafcutter bees to us:
If you see small round holes in your leaves, it is likely you have leafcutter bees nearby. Their favorite leaves, when they can find them, are rose leaves.
Like mason bees, the leafcutter gathers pollen on their fuzzy tummies, not on their legs. They are excellent pollinators and as foragers they are generalists that enjoy many types of flowers. It is said that one leafcutter bee does the same amount of pollinating as 20 honeybees.
These solitary bees usually choose holes in rotted wood or dead trees to build nests in. The entrance to their nests is no larger than the size of a pencil. Once the female mates, she builds her own nest, lays her eggs, and provisions her offspring with ‘bee loaves’ which she kneads by mixing her saliva that contains anti-fungal and anti-bacterial substances with pollen and nectar.
Once the bee loaf is big enough, she lays the egg on top of it and seals off the cell with chewed up leaves. She repeats this process until her nest has no empty cells left, at which time she creates a bigger wall from chewed up leaves to seal off her nest. The new baby bees will remain in the nest until the following spring, when they emerge and the cycle resumes again.
Leafcutter bees do not sting unless they feel provoked or threatened. When they do sting, it is mild compared to a honeybee sting.