Leaf-cutting bees (also called mason bees) are similar in colouration to the common honeybee but are a little smaller and darker with light yellow bands on their abdomen.
Leaf cutting bee-photo unknown
Leaf-cutting bees differ from the honeybee because they are not agressive, are not social and do not normally sting.
Habitat and Lifecycle
Adult leaf-cutters live 2-3 months in hot weather and can lay 30-40 eggs. Females do all the work themselves. This includes finding and preparing the nests, and collecting the food necessary for the young larvae to overwinter in a cocoon (looks like a small cigar) that she builds out of leaves nectar and pollen. Leaf cutting bees build their nests in soft rotting wood and small canes that are easy to bore into.
Damage-photo IPS, International Pollination System
Diet and Damage
They don’t eat the leaves of plants but do cut holes in them and sometimes cut them off to use in their egg cases. Usually the worst that can happen is that your plants, especially your roses will look unsightly. In rare instances some plants, if unhealthy, will die because of the damage. Some years leaf cutting bees can kill many mature plants. Roses and lilacs are the most likely candidates for leaf cutters but sometimes other ornamentals, especially in rural areas, can be chosen. I read an article about people who raise them so their alfalfa crops would have plenty of pollination. They even built shelters for them with pre-drilled holes. These pictures of the larvae, bee damage and shelter came from that website (located in California).
Shelter for Bees built in California-photo IPS
Controlling leaf cutting bees is not usually necessary as any type of bee is great for pollination in your garden but if your problem is severe you might consider using cheesecloth or another protective covering for the plants that are affected. Parasitic wasps and some ground beetles are natural predators. Keeping areas clean of rotting or soft wood may help keep leaf cutting bees away from your tender plants.