Mason bees (Osmia lignaria) and honey bees (Apis mellifera) are valuable pollinators.
They collect nectar and pollen – but only honey bees produce honey.
An increasing number of gardeners are discovering that Mason bees (native to North America) are an alternative to honey bees, which originally came from Europe. In comparison, the somewhat lazy honey bee has been long considered an essential part of the pollinating process for our horticultural and agricultural crops.
“Two hundred Mason bees will do the same amount of pollinating as 20,000 honey bees,” said Julie Kron, Master Gardener, at a meeting of the Fergus Horticultural Society.
The Mason bee appears black but is actually dark metallic blue-green. At first glance, they are easily mistaken for the common cluster fly (housefly). They have longer antennae, smaller eyes, four wings and abdomen with hairs for collecting the pollen
According to Kron, they are solitary, mud builders, living alone, with no queens or workers. Their nests take up less space than honey bee hives.
Because they don’t produce honey, they are not territorial; therefore gardeners are far less likely to be stung.
Nests are constructed with mud or pasty plant fiber. Most build mud partitions between a linear series of brood cells. These compartments are for the next generation larvae. Soil, hollow plant stems, empty snail shells and holes bored into wood are preferred choices.
The female is approximately 14mm (1/2-3/4 inches) long. The male is smaller, about 11 to 12mm (1/2 inch) in length with white hair on the head and chin. Males can be identified by longer antennae and a tuft of white hair at the front of their head and chin.
Due to their solitary nature, Mason bees are immune from attacks by the Africanized honey bee. Since they don’t have hives or honey, they are of little interest to other insects or animals.
Native bees have other advantages. Recently, honey bee populations have been attacked by Varroa destructor and Varroa jacobsoni parasitic mites that feed off the bodily fluids. Most native bees have natural resistance to these parasites. They are also immune to many of the viruses that attack other species of bees.
Honey bees seem to have distinct preferences and usually follow the blooming cycles of certain plants. Mason bees seem to locate flowering plants that honey bees have passed by or have little interest in pollinating.
Because of their use by growers, they are also known as Orchard bees. They are very beneficial to collecting pollen from the blossoms of fruit trees.
Orchard mason bees are very effective pollinators because of their pubescence or hairiness. This enables them to carry pollen grains from flower to flower, causing pollination to take place.
Two or three females can pollinate the equivalent of a mature apple tree in one season.
Unlike honey bees, Mason bees fly in cool, rainy weather, making them particularly attractive for early blooming vegetable crops.
According to Kron, “The home gardener can easily attract Mason bees with blocks of wood with holes 7 to 8mm (5/8 inch) drilled in them. These blocks can be hung in a sheltered area for protection from the weather.
Mated females will use existing holes for a nest. A mud plug is placed at the end of the tubular nest and they will deposit many loads of nectar and pollen at the end of the tube. Once sufficient food has been collected, an egg is laid in the cell and then sealed with a thin plug of mud.
The whole process is repeated for each egg. Often the last cell is left empty to discourage predators.
The female Mason bee lives for about one month in the spring. They lay one or two eggs each day.
Suitable nests can also be created with cardboard and paper straws. The cardboard and the straws should be bundled together and wrapped in weather resistant tar paper or inserted into a large plastic tube.
Bees and flowers have a special relationship. Honey bees and orchard mason bees drink nectar from flowers and collect pollen as well. In return, they pollinate the flowers and these plants can start a new generation of plants.
When people think of bees they often think of honey bees. However, native mason bees are also excellent pollinators and are quite different from the cultivated honey bee.
Ron Stevenson is a member of the Fergus Horticultural Society
