Orchard Mason Bees in Michigan

Why They're Important

• Pollen sticks on orchard mason bees' bodies as they feed on flowers' nectar, and they carry that pollen to other flowers, pollinating them. Many of those flowers become fruits. Although honeybees also are pollinators, their numbers are dwindling. Orchard mason bees can either substitute or augment honeybee populations. Because orchard mason bees become active earlier in the growing season than honeybees, they can pollinate early-blooming Michigan plants while honeybees cannot.

What They Look Like

• Orchard mason bees are a little smaller than honeybees. At first, they appear to be black but are actually a shiny, dark blue with a metallic sheen. Females are about 1/2-inch long while males are a little smaller. Each has small hairs all over its body with a white tuft around the mid-body area, or thorax. A male may have a tuft of white hair on its head.

What They Eat

• Orchard mason bees forage on a variety of flowers that grow in Michigan. They often visit the flowers of common dandelion (Taraxacum officinale), hardy in U.S. Department of Agriculture (USDA) plant hardiness zones 3 through 10, Oregon grape-holly (Mahonia aquifolium), hardy in USDA zones 5 through 8, and roses, hardy in USDA zones 3 through 10. Perhaps more importantly, they pollinate apple trees (Malus spp.), hardy in USDA zones 4 through 8, and plum trees (Prunus spp.), hardy in USDA zones 4 through 9, along with other food-bearing trees. All the USDA plant hardiness zones vary according to plant variety.

How to Attract Them

• Attract orchard mason bees by constructing a nest similar to the type of nest they seek naturally. These bees nest in tubular holes created by other insects or by environmental factors. Recreate those conditions by drilling 3/8th-inch-diameter holes that are 3 to 6 inches deep in wood blocks. Alternatively, buy or create nests with bundles of paper straws. Place a nest where it will be exposed to morning sunlight, near a food source and near a source of mud, which the bees use to plug the nest holes after eggs are laid inside the holes.