Fruit Trees Benefit from Mason Bee Pollination Services
A mason bee (Osmia spp.) with pollen on its legs, back, and body in the San Gabriel Mountains, California. Photo copyright Hartmut Wisch.
Bees in the genus Osmia are collectively called mason bees or orchard mason bees because they cap their nests with mud. Mason bees, along with leafcutter bees ( Megachile spp.), make up two main groups in the Megachilidae family. Mason bees are abundant throughout Europe, the Mediterranean basin, southwestern Asia, and western North America. They are also found in eastern North America and eastern Asia, but are less common; these bees are not found in the southern hemisphere. Mason bees are typically metallic green or blue, but some species are blackish colored. Mason bees are easily recognized because, unlike most bees that carry pollen on their legs, they carry pollen on the underside of their abdomens. Generally mason bees are good pollinators of blooming fruit trees, such as apple (Malus domestica), apricot (Prunus armeniaca), peach (Prunus persica), plum (Prunus spp.), cherry (Prunus spp.), and pear (Pyrus spp.). They also pollinate strawberry (Fragaria spp.), raspberry (Rubus spp.), blackberry (Rubus spp.), cranberry (Vaccinium spp.), and blueberry (Vaccinium spp.).
Several species of mason bees are currently being used or are being studied for use as commercial pollinators. The hornfaced bee ( Osmia cornifrons ) is the primary pollinator of apple orchards in Japan, and has been cultivated for this purpose. It was introduced to the United States in the 1970's and is managed commercially to pollinate apple orchards in California, Oregon, and parts of the northeastern United States. The blue orchard bee ( Osmia lignaria ) is a great pollinator of early spring crops, and is managed commercially because it is easily reared, is a highly efficient pollinator, and requires fewer bees to pollinate crops than honey bees. The blueberry bee ( Osmia ribifloris ) is being evaluated as a commercial pollinator of blueberry in the eastern United States.
Mason bees make good commercial pollinators for several reasons. These bees naturally make nests in tunnels in wood and other cavities; this nesting habitat is easy to mimic and mason bees accept artificial nests. Additionally, these bees are low cost and require little care. In some cases mason bees are actually better pollinators than honey bees (Apis mellifera)
because they fly in cooler weather and individual mason bees move more between
trees.
A blue orchard bee (Osmia lignaria). Photo copyright Hartmut Wisch.
Mason bees are solitary bees. Solitary bees usually build and live in individual nests rather than in a hive or with a colony of bees, while social or communal bees do live colonially in hives or bee communities.
Mason Bees
A mason bee (Osmia spp.) in the San Gabriel Mountains, California. Photo copyright Hartmut Wisch.
Osmia spp.
Description:Mason bees are typically metallic green or blue, but some species are blackish colored. Most have hair on the abdomen, giving them a fuzzy appearance.
Life History:Mason bees are solitary nesters, but are gregarious so prefer to nest in groups. Males emerge in the spring and females emerge several days later, living for about six weeks. Females mate soon after emerging and begin nesting within three to four days. Females lay a single egg on a nectar-pollen provision and then seal the cell with a thin mud plug. The female continues building the nest in this way and then seals it with a thick mud plug, laying as many as 35 eggs. Larvae hatch from the eggs after a few days and feed on the nectar-pollen provision. The larvae then go through a non-feeding pupal stage. Pupae turn into adults by mid-fall and emerge the following spring.
Habitat:Females nest in hollow reeds, holes in wood, sumac, bamboo, and raspberry and blackberry canes.
Distribution:Mason bees are abundant throughout Europe, the Mediterranean basin, southwestern Asia, and western North America. They are also found in eastern North America and eastern Asia, but are less common; these bees are not found in the southern hemisphere.
