The leafcutter bee will cause damage to your rose leaves, but these beneficial insects are good pollinators for your garden.
You may see these small 1/2 inch bees in the garden, buzzing about, or see bees in flowers. They are hairy, black, metallic blue, or purple and shiny.
They cut precise ovals or circles from the leaves that unless you saw them in action, you would think it were a bite from something much larger.
The Cutter bee (Megachile species ) is otherwise beneficial for pollination. A real bees bee, and not a menace.
The damage they do to the rose plant is usually minor, and not worth worrying about. Not all bugs on roses are bad. It is important that you learn which ones are "good" so that you don't harm the beneficial insects such as the leafcutter bee.
The leafcutter bee does not use the leaves for food. They do not eat the leaves,they are used for nesting. The female bee will cut circular pieces from the leaf tissue of your rose plants to line their nests and to plug their egg cells.
Accumulated dead rose twigs or other plant twigs, are where the leaf cutter bee makes her nest. The Cutter bee might even use the end of a dying rose stem that is still attached to the plant.
This is just another reason to keep snipped pieces of rose canes picked up and removed from the garden!
These native bees are not aggressive. They are solitary bees, that do not live in colonies.They sting only when handled. Their sting is considered mild, when compared to a wasp or yellow jacket sting.
You should cut away any dead stems and remove them from the garden.
You should also remove any dead twigs or plant debris, thus taking away potential nesting sites for the cutter bees.
Sprays are Not recommended for the leaf cutter,due to the fact that the bee is a beneficial insect. Why would you want to destroy an insect that is helping your flower and rose gardens, by pollinating them? They are very beneficial to the environment by pollinating not only the flowers in your garden, but wild flowers, fruits, vegetables, and alfalfa as well.