the leafcutter bee

The Leafcutter Bee

The leafcutter or leafcutting bee is a fascinating species of bee belonging to the genus Megachile which also includes resin bees and mason bees. This belongs to the much larger Megachilidae cosmopolitan family made up of solitary bee species.

Leafcutter bees have gained their name due to their ability to cut out leaves and petals from plants to repurpose for their nests. It’s important to note that, unlike many other bee species who chew organic matter for their nests, leafcutter bees actually cut out entire sections of leaf and return them intact to their nest to begin building with.

What do leafcutting bees look like?

In terms of size, most leafcutting bees are very similar to the western honeybee. Their bodies are dark in colour and but they have one key difference that makes them easily distinguishable from their much more common relatives.

Unlike honeybees that store and carry pollen on their back legs, leafcutting bees are equipped with a set of hairs (scopa) that line the underside of their abdomen.

This often gives leafcutter bees the appearance of a lightly coloured or orange abdomen caused by the excess build-up of lightly coloured pollen.

Leafcutter bees are spread throughout the entire United Kingdom but with a much higher population in the south of the country due to the warmer summers and milder winters.

How do they cut leaves?

As their name suggests leafcutter bees are adept at cutting leaves to help them build nests for their young. They use powerful mandibles to cut out sections of leaf and foliage before storing them between their legs for their return flight.

Plants that have been visited by leafcutter bees display clear signs of foraging, you’ll see semicircles cut into the leaf starting from the edges. Check out the image below which show the handy work of a leafcutter bee.

Image credit People Plants Schools

How do leafcutter bees make their nests?

Before they begin to construct their nest female leafcutter bees will seek out a suitable nest site. Leafcutter bees prefer to nest in long cylinders (this is known as cavity nesting) and their nest locations include:

  • Plant stems
  • Holes in the ground
  • Holes in wood
  • Man-made structures with cylindrical cavities
  • Old snail shells
  • Hollow twigs

Once they’ve picked a good site to start constructing their nest they will begin to forage for nearby leaves to create the nest’s internal structure.

Inside the nest

Once the female leafcutter bee finds a suitable nest site she’ll start arranging her segments of leaf in an overlapping tube within the cavity. Some species of leafcutter bees will replace segments of leaf with petals as their building material of choice.

Each segment of a leaf will become a nest cell ready to harbour larva that will eventually mature into a new generation of bees.

Initially, the female leafcutter bee will place an egg in each cell with a small deposit of pollen for sustenance as the larva matures.

The male larva is placed at the top of the nest closest to the entrance with the female larva occupying the cells deeper within the nest, after each egg is laid the female will diligently cover it with another segment of a leaf.

These eggs will eventually become larvae and overwinter within the nest until they emerge the following spring as fully mature leafcutter bees.

Conclusion

While leafcutter bees have very different characteristics from the more common honeybee and bumblebee they are fantastic additions to any garden or wild space.

Despite their behaviour, their impact on plant life is negligible and it would take considerable amounts of leafcutter bees in one location to cause any adverse effect on flora in the area.

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