To pollinate your fruit trees, attract these to your yard Mason bees

By Sara Scudier

OSU Extension master gardener volunteer

The orchard mason bee is the common name of a solitary native bee (Osmia lignaria ssp.) that is very good at pollinating fruit trees.

These are the small, blue-black metallic bees you see buzzing around this time of year.

They are important pollinators of orchards and other spring-blooming plants, shrubs and trees.

They are not aggressive, and thus a great option for incorporating into the home landscape.

These bees do not live in hives.

Instead, the females nest in hollow stems, woodpecker drillings and insect holes found in trees or wood.

They are comfortable with other female mason bees and gladly build their nests close to one another.

This means that fruit growers are able to provide hollow tubes and the bees will nest near the orchard, ensuring next year’s crop will be pollinated.

Home gardeners can also provide a homemade or store-bought bee house or block in their yards to encourage these very important bees.

They are active for only a short period of time during the early spring.

They often emerge when the redbuds (Cercis) that are in bloom, just in time to pollinate apple and peach trees.

The males emerge first and wait for the females to appear.

Females then begin collecting pollen and nectar and lay eggs.

The females carry the pollen on their bellies and do not have pollen baskets on their legs, as do honey and bumble bees.

She forms a small ball of pollen and nectar in the back of the nesting tube and lays an egg on the ball.

She then collects mud to form a cell partition and repeats the pollen ball-egg laying process until she reaches the mouth of the tube, which she caps with mud.

This use of mud is why they are called mason bees.

The first eggs laid develop as females and the last eggs laid in the nest are usually male.

Their short foraging range is about 100 yards from the nest. Activity continues for four to six weeks, then adults die.

During the summer, larvae develop inside the nests, make cocoons, and become new adults resting in the cells.

With the onset of fall, the adults become dormant as they go into hibernation.

These bees require some cold temperatures before spring in order to break their dormancy.