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leaf cutter bee

Q: My sister showed me a rose bush with damaged leaves. Was this caused by a bee?

Q: I was visiting my sister-in-law in Ponte Vedra a couple of days ago and she showed me a rose bush with damaged leaves.  The leaves were systematically bitten on the outside edge and each bite was about half inch in diameter, perfectly round except where the bite was made at the outer edge.  She took it to garden center at hardware store, they said the holes were made by a bee and that was where they had built a nest and then left.  What do you think?

A: I suspect it is a Leaf-cutting bee ( Megachile species). This bee chews on many plants such as the Virginia creeper or ash trees but roses are a particular favorite. The cut out in the leaf is always a neat elliptical shape which makes it easier to identify than the cuts of beetles. 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. The nests are made in tunnels in rotten wood, hollow plant stems or in flower pots and seed trays, especially where the compost has dried out. This is the work of leaf-cutting bees that use the leaf segments in the construction of their nests. Each leaf will be 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 process is repeated until the nest may contain between 20 to 40 cells. These bees are solitary with each female having her own individual nest that she constructs and provisions on her own. The females have stingers but lack aggression and do not chase or sting people. Most plants tolerate the damage, although small plants may suffer a significant loss of leaf area. Like all bees, leaf-cutters are beneficial in the garden as they act as pollinators of flowers, so they should not be persecuted unnecessarily. If small plants are suffering significant leaf loss, swat the bee when it comes to collect another piece of leaf, cover the roses with netting or “grin and bear it.” 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.