About this time you may notice nicely cut outs in your leafs. Specifically roses but other juicy leaved plants will do as well.
No worries, this is most likely the work of a leaf cutter bee. These are solitary bees, quite friendly, only the females have a sting and their main defenses are their tools. The have a good set of mandibles which the use very efficiently to cut out parts of the targeted leaves and only use in anger usually only defending themselves when squeezed or antagonized.
The adult bees are more hairy and broader than a honeybee. Leaf-cutting bee females are 10-15mm long and the underside of the abdomen is covered in ginger hairs.
Females in the wild create nests in small holes in the ground or in available cracks or holes in trees, old vines, buildings, anything suitable.
The nests are composed of a string of individual cells, sometimes up to 20 if space allows.
Watching them is quite fun. Once one has located their nest, mostly close by where they work, its amazing with what efficiency the Bee selects yet another leaf, cuts it, rolls it to the underside and off it flies. Landing and dragging the peace of leaf into the hole. Here the Bee selected a hole in one of our old vines and is happily cutting away at the mirabilis more or less just below.
Each cell is made from circular disks cut from plant leaves using the bee’s mandibles, hence the name «Leafcutter». Each thimble-shaped leaf cell is then stocked with a mixture of nectar and pollen on which the bee lays an egg, before capping the cell with circular pieces of leaf. The larva develops rapidly, consuming the pollen ball and entering a sate of dormancy when the pollen is fully consumed. The next spring, the mature larva pupates and completes its development. Once the bee is developed it cuts its way out from the nest.
The nests are sometimes found when plants are being repotted or old seed trays emptied. The leaves may have become grayish brown and the cells may contain white grubs which will pupate and emerge as adult bees the following year.
These bees are solitary with each female having her own individual nest that she constructs and provisions on her own. Most plants can tolerate the damage. It may look a bit unsightly but is very likely to only appear on one plant. Smaller plants may suffer a significant loss of leaf area. Nests in flower pots have little impact on the plant unless it is growing in a small pot.
Just let them be a bee.
Like all bees, leaf-cutters are beneficial in the garden as they act as pollinators of flowers, so they should not be disturbed or chased unnecessarily. If small plants are suffering significant leaf loss, swat the bee gently when it comes to collect another piece of leaf. It is quite possible that all the damage on a plant is due to a single bee, as it will repeatedly visit a plant that has suitable leaves.
It is really mesmerizing to watch them. Although yet another set of sub letting I don’t mind as they pay rent in form of pollinating.